How Do I Lay A Concrete Slab For A Dog Kennel?

Same way you do for a driveway or any other slab. You basically have to dig down at least four inches, put down bed of gravel, compact it, then have one continuous pour of concrete. Smooth with concrete rake, put expansion cut joints every four feet. Not any easy job, especially if never done before - you only have one chance to get it done right. Plus temperature has to be above 40 degrees for concrete to cure, which can take two days. You could use large patio blocks or other materials that are easier to use and don't cost as much.

It's actually not that difficult, but it can be backbreaking work.  If you've never poured concrete, go get a Sunset book (or similar) at Home Depot or the library to show  you how.

Stake out the area with 2x4 forms.  Put down a layer of sand, then lay in rebar with stand-offs.  Get concrete either premixed or rent a mixer and mix your own.  Pour it and screed it level.  To make a nice finish, broom sweep it at the proper time.

But if you want an easy way to put down a small surface, you can do it with paving stones, or even concrete backer board on a bed of sand.  That makes it easy to pull up if your plans change later.