Step 1 install an irrigation system.
Step 2 kill everything off.
Step 3 bring in black dirt, seed, starter fertilizer and put a paper mulch on those hills to hold the dirt. Make sure to use the maximum label application rate.
Be real careful on the amount of water applied each time to keep the dirt from eroding.
I believe you would be best served to hire a local contractor to take care of everything as they will make sure this is a success from start to finish.