Struggling with a custom template for WP

I’m brand new to CSS and PHP and WP templates. As a hobby I’ve been trying to figure out how to take the HTML/CSS website created for my choir and transform it into a WP site to make updating content easier. I’ve managed to make a lot of progress to that end. The home page on my test site (https://chc.arielbenjamin.com/) is pretty close to the original (https://www.coloradohebrewchorale.org/) though I’ve been told I’ve got some validation issues (which I intend to address but just not yet).

What I’m struggling with right now is the Bios page (https://www.coloradohebrewchorale.org/bios.html). When thinking of a creative way to transfer this over to the new site, I was thinking I could divide the page into four parts and then use a custom page template to pull in each. I was thinking I could have the page divided into four posts, I could then have those four posts in a “bios” category and have the posts with a picture in subcategories of “bios” called “pictured-1” and “pictured-2” or something like that. I was thinking I could then somehow write my page template for the bios page to only pull in posts from the “bios” category but that if the posts were in the subcat of “pictured-1” or “pictured-2” it would embed a separate template file accordingly. Where I’m struggling is I don’t know how to do that or if that’s the best way to achieve this. Am I on the right track? Can someone give me a hand? Thanks in advance!