how to "plug in" html code

This is my old site, built with the inferior iWeb, it made it super simple for me to add my html pedigrees. This is what it should look like:
http://www.bonbonchihuahuas.com/BonBonChihuahuas/ringo.html

New WP site, I tried just adding the html in the “HTML” instead of visual. It looks totally different and hard to read.
http://www.chihuahuapuppiesakc.com/ringo/

I have 10 more pages like this to do, each with it’s own pedigree html.

Please keep in mind that I’m very new and know little to no technical speak.

thanks