If you mean to install the ROM then yes;
(1) Make sure you use Titanium backup and backup all the stuff you want to put back on
(2) Start with 100% battery or as near as you can.
(3) Start CWM
(4) Wipe data/factory reset, do not restart the phone or leave CWM yet.
(5) Wipe cache partition, do not restart the phone or leave CWM yet.
(6) Select "advanced" at the bottom of the 1st screen.
(7) On the 2nd screen choose "Wipe Dalvik cache", do not restart the phone or leave CWM yet.
(8) Return to the first screen, using the curled arrow key bottom right of the 3 buttons on the SF2
(9) Choose install zip from SDCard and then use vol up/down to get to the one you want. Press the Home key when you get to it. If you use a ROM that needs the correct Kernel file then apply this before you take the next step of rebooting the system. This is not now necessary on the latest FnC ROM as its built in.
(10) When it completes you can reboot the system (phone)
Best to leave your sim out the first time then turn off data when the phone boots. That way you don`t get mugged for another £1 like I do, but that depends on the sim and contract. Restart the phone a couple of times. Then use Titanium Backup to restore your stuff.