For those of you who, like me, want to Sync files with your PC I think I have answered my own question and found the ideal app. It's called SyncMe and allows syncing via wifi of cable.
It automatically searches for all of the PCs on your wifi and lets you choose which files and folders to sync. It found my PC quickly and then let me choose which folders and files I did and did not want to sync. You can choose to automate syncing so it is done at set intervals or on particular days or particular conditions, or you can sync manually. You can set up different sync jobs with different settings. You can sync either way or both ways.
It is a free app but if you want to use all of its features you will need to donate the huge sum of £1.99! I had to get a loan from the bank but I managed it.
By the way this is all made very clear in the app description before you download.
I am very pleased with it at the moment, and it appears to do everything I need