iPhone keeps restarting

[lilmissae]

I have a jailbroken iPhone, firmware 2.1

I wanted to download some games, so I went to this site:
DELETED...no WAREZ allowed.

I followed the instructions on 'Option 2'
I downloaded a terminal for my iPhone and entered in what they said to type, the next step was to reset, but once I turned it off and tried to turn it back on, the pineapple logo appeared for several minutes and then the screen flashed white, then black.. and then went back to the pineapple logo.. its been repeating this since I restarted my phone 2 hours ago.

When I connect my iPhone to iTunes, the phone does not show up and iTunes becomes unresponsive.

How do I undo what I typed into the terminal, my phone was perfect before hand and I really don't want t have to restore my iPhone again.
But if there is no other option, I guess I'll have to.

I'm not very good with my Mac, I know some basic things and I am slowly learning about the iPhone.. so if I there is a way to fix my phone, please explain step by step


Thank you very very much to anyone who can help.