Step 3. When you see the warning sign, hit Volume Up button to enter ODIN Download mode.
Step 4. You should see screen like below:
Step 5. Download tmobilegalaxys2rootICS.zip and unzip, you should find 4 files in the unzipped folder.
Double click on Odin3 v1.85.exe to run ODIN program.
Step 6. Choose “PDA” then choose the file “recovery-cmw-hercules.tar” and hit the “Start” button.
NOTE: If you are trying to root AT&T Galaxy S2 SGH-i727 Skyrocket, use “SkyrocketCWM18.104.22.168.tar” instead for “PDA”!
DO NOT TOUCH ANYTHING ELSE!!!
Step 7. Your phone will reset in about 10 seconds.
Step 8. Once your phone reboots, connect to your computer as a disk drive and copy the file CWM-SuperSU-v0.87.zip to your phone.
Step 9. Unplug the micro-USB cable then hold down Volume Up, Volume Down, and Power buttons together for about 10 seconds.