I created a fortress, all was going well, had a first floor set up, and I went to dig down. only... across the entire map all it would say is the job was canceled because the stone was damp. did I screw something up?
It seems like you picked an embark site with an aquifier. These are blocks which produce an endless stream of water to adjacent blocks when those blocks are dug out. This makes aquifier layers almost impossible to dig through. Your miners will automatically cancel their dig order when discovering aquifier blocks, but you can order them to dig again on an already discovered block when you are sure you want to remove it.
When you haven't invested too much time in your fortress yet, I would recommend you to start a new one and this time watch out to pick an embark site without an aquifier.
When you still want to keep your fortress, you could try to break through the aquifier with some advanced dwarfen trickery. This is quite hard to do, but not impossible. Still, I would only recommend this to advanced players who already have some experience with how to handle water.
One method is the cave-in method. Dig out a block of stone above the aquifier, at least 3 layers high and at least 5x5 wide. Then let it cave in on the aquifier layer. The falling down rocks will replace the aquifier blocks and turn them into normal blocks which you can then dig through. Unfortunately this only works with natural soil, not constructed walls. So it is unavailable when the aquifier layer is not far enough below ground.
Another method is the pump method. Use screw pumps to pump out the water faster than it can flow in, allowing you to drive back the aquifier and seal it off with constructed walls.