There is two methods of rooting your SGS2
2-Through your mobile itself
1-USB Cable "If you are gonna use PC method"
2-Root Master for windows "Download" If you are gonna use PC method"
3-If you are gonna root ur mobile without pc download root master apk from here
1-Connect your mobile to your PC
2-enable USB Debugging from Developers options
3-Launch Root master
4-Root Master will check your phone
Congratulations you have just Rooted your phone
Open Root Master on your phone.
After your phone is recognized on the interface, please click "Start" to start rooting your phone.
1. It may take minutes to finish rooting. The different phone will lead to the different duration of rooting process.
2. When rooting successfully, your phone will reboot.
After seconds or minutes, you phone will be successfully rooted.
After rooting, you will get the root permission of your phone and use SuperUser to manage your phone. Now you are able to use more hidden features, uninstall unnecessary preinstalled apps, flash a custom ROM, optimize your system, etc. In a word, you will begin to completely master and enjoy your phone.