Help with decompiling mod correctly

[rsod]

Hello.

I want to modify mod that is not open-sourse so I decompiled it using JD-GUI. After setting up Eclipse with Forge using instructions on Forge Wiki (for version 1.6.4-9.11.1.964) and importing decompiled mod I ended up with this:

What should I do to get rid of those errors?

[LexManos]

1) We dont support decompiling mods, contact the author in a correct manor if you wish to see changes.

2) This is retardedly simple, you should know how to deal with it.

3) 1.6.4.. really.... REALLY...

Locked.