Where is Custom Script?

0_o I think i'm a moron or something like that, it seems that everyone here knows where to import or export custom script, but I dont.
I know whats custom text though, so can someone kindly enlighten this noob here? where is custom script?

Map-specific custom scripts can be entered if you go to the Trigger Editor, and click the top icon on the left menu, called <yourmap>.W3X

For the specific triggers, you need to use the action: Custom Script.