Ok so i will help some new members and others have to start hero online from mozilla here If this dosen't work for you use
1. Start Mozilla & Go to Tools >> Add-ons
2. Go to Get Add-ons
3. Write IE Tab and install IE Tab 2 (FF 3.6 +)
4. Restart your browser and go on to it again, now locate to Hero.netgame.com
5. Login and then right click on the side of the website and go to View Page In IE Tab Plus >> Swith Rendering Engine
6. Wait and then start the game and play my friends