Well she has just seen the dwarves defender and loves the idea of being a dwarven waraxe widelding tank with swords bouncing off her armor.
So sorry to ask this but how would u go about being this tank
Why, you should start off as a Dwarf Fighter, of course, who wields a Tower Shield in one hand and a Dwarven Waraxe in the other. For bonus points, tack on some spikes to your armor and shield so you'll be like a walking barricade.
You can never have enough AC, so buy AC increasing items like an Amulet of Natural Armor and the Ring of Deflection. Don't forget to take AC increasing feats like Combat Expertise. When combined with Defending weapons, they will send your AC through the roof.
Put this together and what do you get?
It's pretty bad actually. You occupy a 5 ft square and can only affect the squares in your immediate vicinity. Even if you're enlarged, you still only Large. In an open and mobile battlefield, people will just walk around you (or shoot past you) as they attempt to gank your teammates. It works better in close quarters, but at mid to high levels there will be many means of exotic movement (teleporation, phasing through objects, etc) that you might find yourself outmaneuvered.
Honestly, tanking doesn't work well in D&D because, unlike in WoW, you can't force people to attack you by taunting. The most common reaction to a Dwarfen Defender is for the enemy to walk away at a brisk pace.