php Runner within existing web page template

I'm very new to php Runner so please excuse this if it's a bit basic & if anybody can help then please spell out the suggestion in detail - you won't insult my intelligence!
I'm trying to use php Runner to generate the front end interface pages with a MySQL database and I want all thephp runner generated pages (login, view etc etc) to have the look & feel of my existing site. My preferred way of doing this is that I have a "template" html page with my header & navigation buttons etc and I would like to place the php code from php Runner in a table in this template.
I have had an encouraging start but I'm getting errors that I don't know how to overcome. An example is here: Example login page as you can see I'm getting 3 warnings about headers.
Can anybody advise?
Thanks in advance.