Hi,
1. How do I use magic with both hands?
2. How do I get electricity and freeze magic?

Thanks!

equip a spell to each hand. simple as that

Only I can be Emperor Palpatine!

Well first off, you need the DUAL CASTING perk, otherwise you will just shoot spells on both hands rather than combining them together.

1: equip a spell to your left hand, then equip a spell to your right hand.
2: buy the tomes from a vendor or find the tomes in a tomb.

yeah well as buddy said you need the dual wielding perk to get that actual bonus, though you can fire both at the same time. And to get the other spells you have to buy them in book form first, they are sold by the court wizard of every hold's jarl and the college of winterhold - in winterhold obviously - has a bunch of people that specialize in each school. But in order to get the better spells you have to be better in that school of magic for it to be for sale.

You can find a spark spell during the tutorial. It may still be sitting there if you go back to Helgen but I'm not too sure. Other than that head to the college and ask around for anyone who slings destruction spells.