Welcome to glitch.com
You don’t want to spends a lot of time trying to preview a site that you’re not sure looks good.
In web design, your priorities should be listed like something similar to this:
- Make the actual page itself.
- When the page is out of beta and ready for the public, then start making the preview embed.
By the time you are ready to make a preview, the site will already be the way you want it, and you should have discovered your own way of programming it, which will help a lot in developing the preview embed itself.
And if you make a preview embed, it will be available for all sites allowing preview embeds for links.
A site where you can study it, which I think is really good for online studying of development, is https://www.w3schools.com/
You can study a lot of programming languages there, which includes every web design language you will ever need to make a fully functioning website. Both good looking and functioning.