Jill, after you select your block is it showing a gray scale block? If so, look at the bottom of the Block pop-up. You'll see a series of arrows. Click the single arrow pointing to the right. The block will then change to the block you added color to. Click that block and then try clicking in the center of the quilt layout.
And yes, I forgot, you need to be in Layer 1 View to place a block. Sorry about that!