How can I apply textures in Blenders UV Editor so I guess I have a really basic question here. I wanted to apply a texture to my mesh trough the UV Editor. I opened a new Image but here comes the first problem already. 
I can't move/ scale the image. 

I need multiple textures on the same spot (Specular, Diffuse, Normal). Once for the front side and once for the back side. 
Do I have to do that in photoshop or is there a way to move images around in the Blender UV Editor? When I am looking for tutorials I only find how they export the UV out and edit it in a seperate software.
You may try using a Stencil mapping option. In UV Editor set the mode to Paint. Add two textures in a Texture panel using the '+' button. Change the brush mapping type to Stencil.


Your texture stencil should appear. Press Image Aspect button to get the original picture dimensions. Hold Ctrl+RMB to rotate stencil, Shift+RMB to change its size and RMB to pan it. Then paint.


Click on the texture preview window, choose your second texture (Up/Down Arrow, Enter or choose it from the textures list) and paint again.


You can use the same method in a 3D View window. It's very useful for blending/hiding the seams btw.