Find a good FC that's willing to help you get experience in end game content. Explain that you're new and need practice. They'll probably ask you to watch a walkthrough on youtube before you try it, but a good FC will work with you and help teach you what you need to know to get through the instance.

Since you're coming up on 50 it's never too late to start earning tomes, though. If you're not already working on it you probably should. Doing the beastman dailies will get you tomes.