How do I edit a .gma file?

[cleveland brown skylander]

I've been wanting to fix a couple of old addons and edit them, but I don't know how to edit them properly.

notepad++ seems to work, but a lot of text is bugged and doesn't appear properly.

[NimrodAbsolution⁧⁧98]

how do i google

[ARZIAC]

Gmas are a type of compressed file. You need to extract them using a program within gmod called gmad.exe

Go to google and do a learning how to do it