In other words, don't try to imitate Albrecht Durer on your first woodcut. After that dries, draw on it with a Sharpie pen. Then, when you have cut the negative space away, you will be able to see where you have cut. Otherwise, you can just to draw on the wood with anything you have, then cut away everything that isn't the picture. It's hard to see what you are doing this way, but the results can be exquisitely beautiful.
Water based inks are easier to clean up, but give different aesthetic results.
Squeeze a dab of ink onto the glass. Roll your brayer over it, so that it spreads the ink evenly on the roller. Roll the brayer horizontally, then vertically. Roll the ink onto the woodblock. Keep rolling up until the woodblock is evenly coated, but not too much.