For coop ideas, I suggest you look in the Coop Designs section at the very top of this page. Lots of ideas there.
Most will go with more than two chickens. They are social animals and if something unfortunate happens to one, then if you have three or more, they still have company. But if you only have two, that is what you have and you need to plan for that.
I'd suggest a coop about 4' x 4'. That is a little larger than the absolute minimum, but with so few chickens, the averages don't mean a lot. With a 4' x 4' you will have enough room for feeders and waterers, a nest box, and a roost. If you get much smaller than that, it is hard to fit all that in there. Plus most building materials come in 4' or 8' dimensions. If you build a 4' x 4', you can use the material pretty efficiently and it should not cost you much if anything more than building a smaller coop.
Along with the coop, you need to provide them a run. That is a fenced in area where they are reasonably safe from predators and cannot go away and get in trouble. For those two, I'd suggest something in the range of 4' x 8' as a minimum. If you can make it a bigger that would be better. Again, this size recommendation is based a lot on the standard sizes of building materials. This size would also work for three hens if you happen to get another.
Good luck! And welcome to the forum.