For the OP. I am glade you're interested in learning how tanks work, it will only make you a better player. As a GLD you should have no issue holding two mobs, providing you get 3sec at the beginning of the fight to get some threat going. Three to four mobs gets a bit tricky, depending on who you got as the rest of your team, but shouldn't be an issue.

This is what I do, it's not the the only way or the best way, but it works.

Typical 3 mob pull.

Shield lob
Flash
Fast blade
Switch target savage blade
(After level 26) switch target RoH
Flash
Back to target one using what ever combo I need. Switching to other mobs to see the threat meter. If its low or on someone else I use SB or RoH on it.
When the first target is almost dead I use my shield lob macro and continue.

Use flash when it's needed. And if you lose threat, provoke, flash combo on him. If needed shield lob