setting up "areas"

I was able to install and run the admin without a hitch, and have created a test pages and see more or less how it works. Then i took a real page to have a second go around with the admin function to insert text, named the "page" with the real page name, got the developer code into that page and uploaded it and voila...

After doing an insert text from admin area i get the developer code and put that in the page i want to use, then upload the file (after converting it to php from html) and the inserted text will show up, as the record i just created with the admin function pushed a record from the database to that part of the php file i just uploaded.

So if i have multiple areas of a page i will have to use multiple developer codes on that page for each part of the page, or is there another way?
so if i have a client change the part of a h1 tag then the code would be placed
inside the h1 tag.

and so on for the paragraph following.. that is <p> ...developer code...</p>
would preserve the styling for these tags.

For files that have already a lot of content, i would have to go thru and get several developer codes for all these areas of the page, interspersing the dev. code. in between all the tags. Is there a better way?
Also is there a way to just leave the developer code in place but without any text? Can you think of a reason why i might want to do this?
thanks!