Check out wowroleplaygear.com. They have galleries with lots of sets sorted by armor class. I can also recommend worldofwardrobes.com if you want to browse items by colour, armour type etc.
And if you haven't already download Atlasloot or MogIt addons.
How you transmog:
Go to any big city.
Talk to guard, ask him about Transmogrification.
You will get marker on map and minimap where the NPC is.
Talk to NPC.
A window will appear that looks just like your character screen.
There will be arrows next to your items, when you click that arrow a grid will appear with transmogs you can choose from.
Any gear you have in your bags or bank that you can use (Leather ONLY for Monks) will be shown.
As a monk, you can transmog melee weapons into any other (the restriction is you cant mog polearm/staff into any other kind of weapon, just to polearm/staff respectively). So you can have Sword but you can mog it into a Fist. You can't mog legendaries or into their looks.