How do you change the sky texture in UDMF?

[THMG]

Basically, the question is in the title. I'm in the middle of designing a map, and realizing that the default doom 2 sky doesn't quite work, I'm trying to change it. Yet, I can't find where the Sky texture is defined. Where would that be, in the TEXTMAP lump? (I've tried using ctrl-F, but every sector in my map has F_SKY1 as its ceiling, so I haven't found it yet.)

[Empyre]

You can set the texture used as the sky in MAPINFO:

https://zdoom.org/wiki/MAPINFO

[Expolision Studios]

What program are you using? 

If you're using Doom Builder, then select the ceiling, go to sidedefs, then select a sky texture. It won't appear as a sky (the kind that LOOKS like a sky) in the editor, but it will show up as soon as you play the map. 

 

If this isn't helpful, then your best bet is to go to the ZDoom wiki, or YouTube.