Right click F1 2013 in Steam > Properties > Local Files tab > Verify Integrity of Game Cache
This will remove any mods, and automatically download and repair any missing, or broken files. It will ensure that you have a standard, fully patched game
How to do the mods etc is mostly pointed out in the thread you are dl the mod from.
If you have problems with a mod, you can make a post were the mod is ......