Mmm... Well, XYZ summoning's pretty easy. The card has a summoning condition of 2+ monsters that fit the prerequisites of the card; both monsters have to be the same level in order to 'Overlay' the XYZ on top. The two monsters are placed onto a single monster zone and the XYZ is placed from the extra deck on top of the two+ cards. They also have ranks, not levels (so things like Gravity Bind... They really don't care about). 

I'll use Evilswarm Exciton Knight as an example. It's a generic rank 4 XYZ that requires two level 4 monsters to summon, so I need those two out on the field before I can use them. I can overlay Exciton on top and, if I fill the requirements for his effect, I can detach (aka remove materials from under the card) to activate it's effect.

And given that we're using 5Ds rules... First turn draw six? Oh boy.