Hi Stephanie,

You have not said what OS X you are using... If it is Lion your home library is 
hidden.
You have to unhide the home user library in OS X 10.7 Lion.

Show User ~/Library in OS X Lion
Launch Terminal from Spotlight or Launchpad -> Utilities, and enter the
following command to show or hide the directory:

chflags nohidden ~/Library/

The users Library folder will immediately become visible again. 
OR, even easier:
Just press and hold the “option/alt” key, and you can choose 
“Go to Library” in the Go menu of the Finder.

Also if you have not backed up before, there won't be a backup file in 
~Library/Applications Support/MobileSync/Backup

Cheers,
Ronni
Sent from Ronni's iPad

On 04/07/2012, at 9:25 PM, stephanie dowden <stephanie.dow...@gmail.com> wrote:

> Hi again,
> 
> Long story, but transitioned from old iBook G4 and old mini mac to MB
> air and ipad, but sorting out to do (when back from hols) so just
> needed an interim solution (thanks). BTW nothing called mobile sync or
> back up under ~Library/Applications Support...
> 
> Stephanie
> 
> On Wed, Jul 4, 2012 at 8:38 PM, Ronda Brown <ro...@mac.com> wrote:
>> Hi Stephanie,
>> 
>> As I mentioned before you set up what you wish to sync to each iPhone.
>> Select what Apps, books, music etc. When iTunes backups the iPhone it will 
>> backup everything you have synced to the iPhone.
>> 
>> You indicated you were using both iPhones on one computer with two user 
>> accounts?
>> Now you mention you have a MacBook Air?
>> 
>> iTunes stores the iPhone backups in ~Library/Applications 
>> Support/MobileSync/Backup
>> The ~ indicates your User home library.
>> 
>> Cheers,
>> Ronni
>> 
>> Sent from Ronni's iPad
>> 
>> On 04/07/2012, at 8:16 PM, stephanie dowden <stephanie.dow...@gmail.com> 
>> wrote:
>> 
>>> Hi Ronnie,
>>> 
>>> Wonderful response (as per usual) - and it's worked so far: I Backed
>>> Up (photos went to iphoto and I assume remainder went to itunes. Do I
>>> need to specify sync of apps, music etc or will it do this as part of
>>> the back up? Also - where does itunes store the iphone back up? (I've
>>> a new MacBook Air)
>>> 
>>> Stephanie
>>> 
>>> On Wed, Jul 4, 2012 at 7:43 PM, Ronda Brown <ro...@mac.com> wrote:
>>>> Hi Stephanie,
>>>> 
>>>> Glad to see you have come down from hovering ;-) Welcome to WAMUG.
>>>> 
>>>> You mention you have separate administrator user accounts on the laptop.
>>>> 
>>>> iTunes will see the iPhones as two totally different iPhones, so there are 
>>>> no issues with multiple iPhones.
>>>> The way to manage different music is to set up a playlist or playlists for 
>>>> each iPhone and just sync those playlists to the iPhone you want.
>>>> 
>>>> Instructions:
>>>> 1.The first step to hooking up two iPhones to one computer is to make sure 
>>>> that the iPhones have different names. Chances are your two iPhones 
>>>> already have different names as they are probably used by different people.
>>>> When you first connect the iPhone to a computer, iTunes will ask you to 
>>>> name the iPhone. Just make sure that you name the two seperately.
>>>> 
>>>> 2. Next, sync up each iPhone one at a time. When you connect each iPhone, 
>>>> iTunes will recognize the unique name and allow you to set up your 
>>>> playlists, photos, etc. unique to that iPhone.
>>>> When you are done setting up the first iPhone, do the same with the second 
>>>> one.
>>>> 
>>>> 3. To have two separate sets of contacts, create two groups of contacts in 
>>>> your address book (on a Mac). Then under the Info tab in iTunes (after 
>>>> selecting your iPhone icon), select which contact groups you want to sync 
>>>> for that iPhone.
>>>> 4. That's it! It's that easy to set up two iPhones on one computer thanks 
>>>> to Apple's simple programming.
>>>> Cheers,
>>>> Ronni
>>>> 
>>>> Sent from Ronni's iPad
>>>> 
>>>> On 04/07/2012, at 6:47 PM, stephanie dowden <stephanie.dow...@gmail.com> 
>>>> wrote:
>>>> 
>>>>> Hi,
>>>>> 
>>>>> A query about syncing an iphone...
>>>>> 
>>>>> We are going on hols and taking laptop, ipad and 2 iphones. One phone
>>>>> has been unlocked (as out of contract) which will take '5-72hrs' so we
>>>>> need to back up the phone, restore to factory settings and then
>>>>> restore it from the back up.
>>>>> 
>>>>> Do I need to install another itunes (as we have 2 separate accounts),
>>>>> or can all our devices be on one itunes?
>>>>> 
>>>>> Thanks,
>>>>> 
>>>>> Stephanie
>>>>> 
>>>>> (Proudly paid up WAMUGer after being a hovering in the background,
>>>>> reading and learning lots freebie for the last year)
>>>>> 
>>>>> 
>>>>> 
>>>>> --
>>>>> Stephanie Dowden
>>>>> 
>>>> -- The WA Macintosh User Group Mailing List --
>>>> Archives - <http://www.wamug.org.au/mailinglist/archives.shtml>
>>>> Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml>
>>>> Settings & Unsubscribe - 
>>>> <http://lists.wamug.org.au/listinfo/wamug.org.au-wamug>
>>> -- The WA Macintosh User Group Mailing List --
>>> Archives - <http://www.wamug.org.au/mailinglist/archives.shtml>
>>> Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml>
>>> Settings & Unsubscribe - 
>>> <http://lists.wamug.org.au/listinfo/wamug.org.au-wamug>
>> -- The WA Macintosh User Group Mailing List --
>> Archives - <http://www.wamug.org.au/mailinglist/archives.shtml>
>> Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml>
>> Settings & Unsubscribe - 
>> <http://lists.wamug.org.au/listinfo/wamug.org.au-wamug>
> 
> 
> 
> -- 
> 
> Perth
> Western Australia
> -- The WA Macintosh User Group Mailing List --
> Archives - <http://www.wamug.org.au/mailinglist/archives.shtml>
> Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml>
> Settings & Unsubscribe - 
> <http://lists.wamug.org.au/listinfo/wamug.org.au-wamug>
-- The WA Macintosh User Group Mailing List --
Archives - <http://www.wamug.org.au/mailinglist/archives.shtml>
Guidelines - <http://www.wamug.org.au/mailinglist/guidelines.shtml>
Settings & Unsubscribe - <http://lists.wamug.org.au/listinfo/wamug.org.au-wamug>