transferring files

What files are you moving? The method differs depending on what you want to do.

I am trying to move vehicle icons.

One more thing may be i explain myself more clearly.

I would like to delete the vehicle icons from inside my C510 making a back up to my P.C.

But in case i would like to re-install the icons into my Garmin set what shall i do (If it is Possible)

I have a Garmin 680 but I believe it is set up the same way. To delete vehicles:
1- plug your GPS into the USB plug from your PC.
2- left click on Start (I'm assuming it's not a MAC)
3- right click on Explore
4- go down to the directory that shows your GPS. Mine says +Nuvi (H:)
5- click on the + sign of the GPS directory
6- you'll see a directory called +Garmin
7- click on the +sign of Garmin
8- now you'll see a directory called Vehicle
If you look in there you will see all the vehicles ending in .srf - you can copy them somewhere on your PC and then delete the ones you don't want.

Make sure the device is not marked 'readonly'. Someone had a problem like this awhile back, and found that the readonly flag had somehow been set. You might find that thread with a search on readonly.