My monitor has no signal and my pc won't boot

Hello,

hey, i have a dell dimension 4400 note i don't no that much about computers ! anyways i have a dell dimesion 4400 and i got a new video card for it cuz the other one couldn't support my game! and i rplaced it with radeon 9700 series when i did everything was fine till an error message came up and said that i needed an power extension cable of some sort! so i opened up my machine again and then i saw the two floppys hagging out whatever those two white things are, and theyy had labels like p7 p4 p3 so there was a part on the video card that u could stick in. so i took the small one p4 and sticked it on the side of the radeon, but then when i turned it on it stared making this beeping noise and the monitor had no signal to it! the computer would come on with a beeping noise and the monitor wouldn't come on! i have no clue what's going on? uhm please help me with this issue thankyou!:)