Overlay an image with another image, like in photoshop For my material I have a pretty dark base texture. I want to 'spice' it up with an orange rust texture. I just want this to be overlayed on the base image and to be adjustable. Like two layers in photoshop and the top one you can adjust the opacity. 

I'm a noob at the node editor so any suggestions can help.
Well with a bit of exploration I found what I was looking for. The MixRGB Node. I was using the Mix Shader before and that wasn't working at all, then I realized you can't put color nodes in shader nodes...derp.

Anyways if you wanna Mix together different colors or image textures (anything with a color output) just use the MixRGB node and you get all the awesome blend types like in Photoshop (Overlay, Darken, Multiply etc.)