If you are not using Bitcoin Core, and instead you are using bitaddress.org, then you'll need to make sure that you safely and securely store the private key that bitaddress.org gives you for each address. If you receive bitcoins at an address generated by bitaddress.org, and you no longer have the private key then the bitcoins can not EVER be spent. They will be stuck at that address forever.
Assuming that you have the private key, then you can give out the bitcoin address to others for them to send bitcoins to you. When you are ready to spend them, you'll need to import the private key into wallet software that you can use to create the transaction.
You could go to Recieve tab on Bitcoin Core then click request payment if you don't want to fill out informations. Then you can copy the address when the popup appears.
What you have most probably done is to generate an address most probably at the first page. You can use that address as your main payment address. But before you do anything, backup your "PRIVATE" first either into a textfile or writing it down. Go to HELP>DEBUG WINDOW>CONSOLE and enter
importprivkey (PRIVATE HERE)
It's ok guys!
I figured it out!
I was just a bit confused and totally skipped over the "All fields are optional" bit lol
Thanks for your help!!