How to make a Web App that allows comparison of model drawings?

I’m new to web development and have a mini project which I have been stuck on for weeks. I’m looking to make a web app centred around human ergonomics. The web app should allow users to choose a human model alongside a desk table (of various sizes) to see if the design is ergonomically suitable for workplaces. Problem is that I don’t know what I don’t know so I’m stuck searching for a template of such.

I’ve learnt basic HTML, CSS, JavaScript and even PHP but I am still unsure of how to approach this. Browsed W3schools.com for some templates or anything similar but to no avail.

I have an example that I found online: https://cycle-ergo.com/

The website allows user to select the rider’s size and model of the bike that they are interested in. Hence, this web app link is quite similar to what I would like to make. I would highly appreciate it if I’m given the direction I should learn/refer to make something similar.

Thank you!

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