Video Sharing Websites
The best and the cheapest way to go about it is to see video of the tutorials on a video sharing website such as youtube.com or dailymotion.com. There are various options that are available on these websites and you can pick the tutorials and learn as you please.
This is best for someone who likes to do things on their own. You can pick the tutorials of someone whose style you feel you can connect with. This will provide you with the much needed flexibility that you will require when you start learning.
There are professionally prepared teaching suites that are available in the market and you can buy one of these and learn from them. This will cost you a bit certainly but you will be able to learn from the very best in the business.
You will learn some much needed tips from these guys as well. It is not a bad option if you are looking to take photo editing as a profession. This can also help you in doing a small side business.
Professional Teaching Websites
There are websites such as Lynda.com that teach various graphic related programs. You can subscribe to one such website and make use of the tutorials they offer. They also have a large library which members can access and learn the tips and tricks or get insight from previous projects.
If you are someone who is at home with the basics of the program, this may not be idea for you and you should be able to hone your skills even more.