I just did a google search and came up with lots of sites that show and discuss pruning. I would start there, it's free. Also your county extension office can possibly help. Just remember one thing, lots of trees grow unattended and don't necessarily need pruning. Always prune with a reason in mind. I am not an expert but have always had success with pruning with a plan. If there is a crossing, errant, or broken branch, you can prune it. Prune it to where it meets the main trunk or a main branch. If you lop it off halfway, it will branch out from there. If you prune at the wrong time you can remove the buds for the next year and have no flowers or fruit. Pruning doesn't necessarily have to be done every year. And young trees often don't need to be pruned. So I would suggest starting with the internet, just ask for pruning in general, and then ask about specific plants. Some that are very large may need to be done professionally. Good luck with this.