how can you transfer a pic from pc to a cell phone.

Plug it into a USB port in your computer. Alternatively, you can send it over via SSH/SCP/rsync. That does get more technical if you don't know what SSH, SCP, or rsync is.
 
If you are iphone user, use iTunes. if you are android phone users, the process could be much easier, you just need a USB cable and transfer your files. But of course, there are much easier and quick way. Try FoneTrans http://www.fonelab.com/ios-transfer/ so you can transfer all your files from iphone to computer and from computer to iphone.