I want to put a procedural texture in the background of my image. I set the "World" color to a texture I like, and I would like to change the angle of this texture. How can I do this?
What you want to do is edit the World nodes. Go to the Node Editor and click the globe icon:
Makes sure you check the Use Nodes checkbox as well.
Now add an Input > Texture Coordinate and a Vector > Mapping node and connect them as shown:
Now the three rotation values will adjust the orientation of the texture.