how do you draw a skybox

i am wondering if there is a mathmatical formula for drawing stuff on a skybox. i cant figure out how to put things like clouds or circles or any kinda of thing on a skybox and have it look real and make it so you cant see the edges of the box.

I’m a little lost on how best to create the images with corresponding sides, as well. I do know you set Wrap Mode to Clamp on all the textures, though…