Prayer is honestly a pretty pointless skill. None of the prayers work, and even if they did they wouldn't be of much help in any situation. The only real purpose of prayer is to increase your combat level, and it's just another skill to say you have 99 in.
To train Prayer, simply go to the "Skillz" teleport in your emotes tab and go to the general store shop keeper. Buy orug bones from him and bury them. You'll need 163 bones to get from 1 to 99 prayer. This should be easy, assuming they're in stock. This only takes a few minutes to get 99 in, so you might as well do it to get it out of the way.