I have been fussing with SkyDrive for several days. About at my wit’s end -- this should be simple, but ......

I have a desktop PC under Windows 7, and wife just bought a Surface Pro under Windows 8.

Our files are on the desktop.  I selected several important document folders and picture folders and copied them to the SkyDrive folder on my desktop.  I have changed a couple of Excel spreadsheets using files from their normal location on my PC.  Should I instead Open them from the desktop SkyDrive folder and Save them there also after updates are made?  Will that sync the changes from my desktop SkyDrive folder into my regular folders on my PC?  Also, even though I installed the SkyDrive app on my wife's Surface Pro, only the Pictures folder shows on her SkyDrive folder.  Why didn't mine sync to her tablet?