These errors are telling you that you there is output that has occurred on line 7 of your index page. Due to this output the header call on line 8 will not be executed. What do you have on line 7 in this file? Usually when you see this error it is due to some white space characters being outside of the php blocks. Check the php blocks you have near this line and make sure to update them if there are any spaces or returns present.
If you can't spot it and continue to get the error post back with a current copy of your index page that is producing this error in a zip archive so that I can take a look at it.
