I've seen basic instructions online, but one that I've found work on our shower. This is what I have when I open it up: https://goo.gl/photos/cyDEQVWygrCgsmMw7
Please give detailed instructions, because like I said I find anything that matches.

It appears you have a Peerless single handle shower unit. If this is correct there are some very excellent instructional videos to adjust the temperature on Youtube and EHow.

How to Adjust the Mixing Valve in a Peerless Single Shower Head | eHow

Or

How To Adjust a Single Lever Shower Faucet - Self Help and More

And this is an excellent video.

how to adjust temperature on a peerless shower faucet - Bing video

Excellent Links Talaniman sorry I can't gave you a green it tells me as follows.
You must spread some Reputation around before giving it to talaniman again, Thanks.

John

Picture is not too clear - but I think it is the yellow plastic ring that acts as temperature adjustment. ( It is the one that turns with handle ). Remove it.

Milo