Where do you start? By assigning oxidation numbers to each of the elements to determine which have changed. Here is a hint to get you started. Cr changes from +6 for EACH Cr on the left to +3 on the right. Cu changes from zero on the left to +2 on the right.
You need to learn to do these redox equations yourself. Here is a site that tells you almost anything you want to know about redox equation.
If you have specific questions as you go through I'll be more than happy to help you through.