How do I make a skybox texture?

I’ve looked through google, and I’ve already done a search everywhere… I’ve been trying to make a space skybox but I don’t know how to make the skybox work AS a skybox in hammer. Can someone tell me how to make a texture have the ability to be a skybox?

Also, does anyone know of a good way to make a good looking space skybox? The one I have is okay but I would love to make a better one.

Thanks in advance.

You obviously didn’t Google hard enough.

This was the first result for “source skybox texture”. :v:

Thanks for the help.
After doing that, I learned that the skybox looks horrid, is there a good way of making a space skybox? I tried making my own following a certain tutorial, and everything got messed up.

do you want starfield or with planets and stuff

With planets. That would be fantastic. Just a starfield would be a bit barren.

Find some pictures of planets, colour the bckground black, then paste them into once of your skybox images.