First of all you need to get the size of your image correct. Refer to the page on altering image sizes. Remember its much easier to think in cm or mm than pixels.
So you have your image and its the right size, resolution, etc. Can you mess with the colour balance?
Image > Adjustments > Colour Balance (see image 1)
Should be self evident from there (see image 2)
You can also messs about with other things related to colour, (see image 3)
Select an area using the select area tool in photoshop (image 1)
Go to new adjustment layer > photo filter (image 2)
Select a main colour. What happened? Play until you get the desired effect. (image 3)