I was wondering because I've been searching the internet for how to edit my portal gun i can't find anything at all can anyone help?

The first thing you need to do is extract the materials for the gun from the Portal Content GCF. Then you can edit them and save them to your Portal directory.

This is the easiest best method

That seems very difficult or maybe i'm just stupid but is there any easier way?

1) use gcfscape to extract the materials folder from pak01_dir
2) browse to materials/models/weapons
3) in v_models/v_portalgun grab v_portalgun.vtf
4) in w_models/portalgun grab w_portalgun.vtf
5) use the vtf plugin for GIMP to edit your texture. (or safe it in a format you like to modify it with another program)
6) safe the textures
7) place the textures in steam/steamapps/common/portal 2/portal2/materials/models/weapons/w_models/portalgun and v_models/v_portalgun
restart portal 2
9) profit