dont worry bro, Barb is easy to play..

Can link us your battle.net profile?

we can add you as friend and give you a +300LoH Amethyst gem.
Anyway for weapon with socket put Amethyst for any level below 60 (or any difficulty below Inferno)

Can link us your battle.net profile?

we can add you as friend and give you a +300LoH Amethyst gem.
Anyway for weapon with socket put Amethyst for any level below 60 (or any difficulty below Inferno)

How do u get a gem?
1.During farming when u kill mobs or E.
2. GAH or RMAH
3. Add me la I donate some. 

You can't change difficulties unless you finish Normal Act 4.... unless someone carry you to nightmare in public game. However I advise you keep playing, don't skip.

There are 4 difficulties > Normal > Nightmare > Hell > Inferno.
Monster hits harder/longer HP as the difficulties rises (duh)

Also..there's MP.. Let's just say on MP0, skeleton has 10hp...while on MP10 you multiple the hp & damage by 10. MP also gives you additional Gold/Magic Find and exp bonus.
See this Monster Power

For people who prefer a more challenging/farming game.. they can choose higher MP. However, higher MP doesn't mean you can get better stuff (RNG is RNG).

finished Act 4 Normal -> restart Act 1 Nightmare -> finished A4 NM -> restart A1 Hell -> fin A4 Hell -> welcome to Inferno.

I suggest that for now on you choose the high MP (MP10 ) for fast levelling up.