Cannot modify header information - Problems with embedding

I took my html page and saved as php in propper folder. I then edited top of page for directory information updates. This intergration mostly works on a website. But when using the navigation at top of gallery2 and clicking on gallery to get back to main page, I get an error. Also if you try the admin login you get same error. Any ideas as to where the problem lies? What file do I have to edit? See my screen capture below.