First of all you take the screen by pressing F1.
Then you have to go into the screenshots section in the NBA Live 2004 folder in My Documents (My Documents/NBA Live 2004/screenshots) and open the screenshot in a program like Paint for example and SAVE IT AS A .JPG / .JPEG! This is important.
Then you go to a image hosting site, here is the link for one:
http://imageshack.us/index3.php
you then click on browse and click on the screenshot you saved as a .JPG and then click 'Host it!'. You will be redirected to a new page and it will have your screenshot posted in form. You just copy and paste the [img](your%20screenshot%20here)[/img] into your thread and your done.