Can't install new driver

[Maureen L Thomas]

Ok, so I got rid of the windows machine and found a card that fit the 
old machine.  It needs the rtl_nic driver to work.  Fine I have that 
firmware and the needed driver on a USB stick and on an iso disk for 
stretch.  The USB is just the firmware for these type of cards.  I must 
be losing my mind because I cannot remember how to get the driver to 
install off of the USB to my existing weezy system.  Thank you for even 
reading this but I need help.  I did try apt-get install but it didn't 
find the file on the USB>
Maureen