I'm no electrician, so I'll leave that part alone. Is the MH brand new, or new to you? I would suggest spending an evening reading thru all the manuals that came with it. For the WH, make sure the valve on your LP tank is open. Secondly, turn on your water pump and open the bathroom and even the kitchen hot water. You're trying to purge air in the WH tank and lines. Heating an empty tank is bad bad bad. Once these two steps are done, the switch to turn on the WH is a small (probably black) rocker. Mine is on the control panel above the bathroom sink. It will probably have an orange light it indicating it's on. BTW, if there's air in your gas lines, which there most likely is, turn on a stove burner with a lighter held next to it. Once it ignites, the gas line is 'mostly' purged. Hope this helps.
Lovey & Thurston - Cali Foothills
2001 HR Vacationer (SS Minnow) - Gasser!
Obviously A Lowly and Inferior MH