im not sure what they have disabled but i found i got an error when using the complete URL
What exactly did you try and what error did you get?
i usually use the tab but i cannot use it here
That's because web browsers typically use the tab to move from one form control to another. Writing your code examples in a text editor sidesteps this problem entirely, is safer in the event of a forum glitch.
are there any good tutorials on correctly embeding and indenting php in html?
Not that I know of, but the general idea is the same as in all programming languages descended in basic syntax structure from C (or which requires indentation, e.g., Python).