Building My First Computer And Suprise It Isn't Working
Just going from what you've said, what I'd try is:
Test your monitor with another computer or component to ensure that it works (if you don't already know so).
Try connecting your video card to the monitor with a DVI cable instead of your HDMI cable, if you have a cable handy and assuming your monitor supports it.
Remove the Radeon and dig up or borrow another video card to try in your system.
As long as the computer appears to be powering up now, I wouldn't worry too much about the beeps you heard the first time you booted it up. If you want some measure of assurance that it's still getting as far as the POST in its boot phase, you might try removing all the RAM and then making sure it gives you some sort of beep code when you try to turn it on.
Good luck...
I just finished building my rig about a week ago, haven't built a PC in about 10 years. I can't really say what your problem may be, but I had one problem keeping my PC from booting up that took me a couple of hours of troubleshooting to figure out. It was the power cable from the Power Supply to the motherboard. There should be a 20/24 pin slot on the board AND a 4 pin slot. Be sure BOTH cables from the Power Supply are plugged into these slots. It's not just one cable from the power supply that is used to power the board, but two. I forgot that, or things have changed in the last 10 years.