If you're downloading the app it should find the connection to the site automatically but if, as you said, the site is down then it probably can't access the server on its own. The only other thing you cas do besides waiting for the site to come back up is to check to make sure your internet connection is active and working.
BUT if it's really a black market it probably would be best NOT to download apps from there. You have no idea who's been doing what to those apps and it's an easy way to invite malware on your phone. Give the AndroidPIT App Center
a try if you want a market were the apps are safe and controlled.