If you're not comfortable using Terminal and want to check if you're infected by the Flashback Trojan, a free simple app called Flashback Checker does it automatically for you. If you are infected, then you'll need F-Secure Flashback Removal Tool to remove it.
Using both of these tools, you can check and remove (if neccessary) the Flashback Trojan automatically without having to use Terminal. To use F-Secure Flashback Removal Tool, simply double-click the zip package to unzip it in the current folder. Double-click the FlashBack Removal app to run the tool and then just follow the instructions to check your system and clean any infections
If you're worried you may have been one of the reported 600,000 Mac users affected by the Flashback Trojan, F-Secure Flashback Removal Tool is the simplest way to remove it if you have.