when you're replacing a part or two, you'll get a small amount of air in the line and most of the time that is no big deal. When your lines have ALL air in them they can be challenging. The good news is.... you're at the right place to avoid the learning curve. Just start using the search feature and reading up on it before you start and if you need more help, just post a few questions. It's not really a hard job, it just can be tedious.
My project wasn't lines. It started with the master cylinder. I was bench bleeding it, but had both ends of my rear lines open and lost most of the fluid. It was like starting from scratch. Do a search on gravity bleeding.