Building fixed width table templates…

My purpose in using WP for our company website is so the owner(computer illiterate) needs to be able to edit pages and posts on the fly(CMS). My idea is to have templates set up for him(I have that already)…what I don’t have is a fixed width table(s) inside these templates. WP changes my code automatically. Does this need to be coded in a CSS file/template?
omg…What am I doing wrong?

He wants to be able to just upload photos and type in text without the table expanding…etc…uggh!…lol

Please help and advise.
Thank you.
Sincereley,
David M. Sellers