Once you have completed step 5, you would open your webbrowser and point to the IP of the machine that you have installed it on. (or if you have shared hosts the webpage that you configured for the site.)
Or are you saying that you get to that part, and after filling in all the information and hitting submit you get a black page?
Check the php logs. The location of the php logs varies fairly significantly by implementation and OS, but you can find where yours is by looking at your php.ini. I run OST under Win Server 2008, IIS7, w/ PHP5 so I'm afraid that I cannot get much more specific than that. If there is an error in the PHP logs it should point you in the right direction, or you can post it here and we might be able to assist you further.