hi
It depends on what your data is.
For any quantity of data generated externally, you should first read
https://wiki.openstreetmap.org/wiki/Import/Guidelines and follow the
guidelines there. Otherwise there is a strong likelihood of the change
being reverted.
For the practicalities of using csv
The weekly round-up of OSM news, issue # 394,
is now available online in English, giving as always a summary of all things
happening in the openstreetmap world:
http://www.weeklyosm.eu/en/archives/9998/
Enjoy!
weeklyOSM?
who?: https://wiki.openstreetmap.org/wiki/WeeklyOSM#Available_Languages
