page importing

I’ve been searching in internet but nothing make me clear.

I want make page with my own web page (html + php + css).
No one plugin offers free code editor so i want make as different page.

Problem start when i want this page create under wordpress.

http://wordpress.bla/mypage

i just want merge my webpage with wordpress like that all stays as it is but the page content shows my created page.

i’ve been tried some plugins but some i dont like editing, some leave all fixed position and etc.