Creating a webshop and how to do? Please answers are needed asap.

Hello I am a web development student. Complete begier pretty much.
I am currently trying to build a webshop and I want lines of 3 images next to each other on each page and I have done that on the startpage but I can't get the caption under them?
I tried the HTML5 figcaption-tag but it still messes up so that the images end up not next to each other and it looks very bad.


I also wonder about how it works with the images in a webshop linking to a new page? Like a page with additional information about the item etc. and if it is recommended to put the form for payment on each one of those pages instead of using Javascript to create a cart-icon and all that complicated stuff. I had written in my wireframe that that was the way my webshop was goa work but I think now it's beyond my level of skill.
So anyway do I need to make one extra page for every item on the entire webpage or how does it work? And please explain as basic as you can. Thank you.

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