You have a residential water heater with a block valve (Top) and a 3-way valve (Bottom).
First thing you need to do is close the brass drain valve on the very bottom. Then Open the block valve on then top (P.S. It's open in the photo), and then turn the bottom 3-way valve so that the handle is inline with the water inlet line (90ļ from where it is now).
Then turn on the water and go open a hot water faucet until water runs out. Just to be safe, I'd open them all one at a time.
Then turn on the power to it.
P.S. You can crack open the T&P valve to make sure the tank is full, but it's going to splash water out the pipe, so be ready for it.
Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!