I don't understand your talking ! Do you want to convert HTML template to WordPress theme ? If right please contact me
Wordpress support HTML, CSS and PHP. You may just learn the those necessaries will do while you do not need much of it . Simple HTML will help you.
If you want to create sites in wordpress without needing to ask every singe question on forums, YES. Site owners don't necessarily need to know HTML, because the little editors wordpress comes with takes care of the HTML for them. Are you a site builder? You need to know HTML, CSS, and likely some PHP and Apache's mod_rewrite (wordpress has its own special rules there). Are you a site owner/user? You probably don't need to know anything, though if you're troubleshooting your own site you'll do better with some knowledge.
HTML is very simple to learn the markup is limited and basic. I'd suggest anyone wanting to operate a site to at least have a basic knowledge of css and html. It will undoubtedly assist you in your endeavors.
I would say learning HTML, CSS, and PHP while using wordpress is like Learning how to use a hammer and screw driver if you want to fix a hole in your roof