Hiya
There are probably quite a few ways to do this, I know 3Dkiwi has a tutorial all about round holes and intersections. Ive had a couple of ngons creep in on my corners here but it gives you the basic idea. Grab below
Start with the plane and delete all the points in the middle, select the inner points, I'm showing a line here but you can convert between points lines and pollys. when you have the points selected, use the "collapse" command in the mesh menu, once you have the single pt in the middle, you select that alone and use the bevel tool on that single point, this gives you the ring. Delete the middle polls, select that edge and extrude it, but with a zero offset, this way you end up with a second line in the same place, which you can then just move up into position.
Deck
