You can jailbreak your iPhone using
ziphone. It is the easiest and safest way to jailbreak your iPhone. Download, install, open, click "jailbreak", wait 35 seconds and you're done.
One jailbreaked, you will find apps under "Installer", a new icon that will be on your springboard. Open Installer and browse for apps you want to install.
Install, try and if you don't like the app, simply uninstall.