Thinking about jailbreaking your iPhone? Well, I would say it is worth it. There are so many customizations you can do as well as download free apps.
http://evasi0n.com
You need to download evasion for the firmware you have. To check which version you need go to settings then general and then about. It will be right next to version.
I use evasi0n because it is very user-friendly and quick. However, i'd recommend backing up your data via itunes. Currently, there is a jailbreak 6.1.3 and 7 should be out September 5th.
Comment with questions