How do I attach my part to a center (dead center or live center)?

If you have not center-drilled a hole in your part, first do so. Then, put either a live center (free to rotate) or a dead center (resists rotation due to friction) in the tailstock, and push the tailstock toward the part. Once you are close, lock the tailstock in place, and rotate the crank until the center is fixed inside the hole you drilled. It should now be secure for you to use the lathe! Here’s a video explanation.