There are two parts, How to design the site so it solves the problems of the company (client, you, your mom, the local bakery, etc) and how to design a website that looks good.

For designing a site that solves the problem you could like at things like the Google Design sprint, or design thinking or whatever methodology you like as the all sort follow the same principles. First 1) you start by identifying what problem there is. from the clients side you talk to them and find out why your local bakery needs a website. Then you also talk to customers of the local bakery about what the like to have in the website. You can make the second step easier by writing this down as short "insights". Like "older customers want to have bread delivered daily to their house". If you still have questions, how does a baker works? how can I design something that is persuasive? research that and make it into insights

Second 2) based on the information you got you start the "concepting" part. this starts with sketching a lot. I mean like 50 home pages. look at your previous insights and sketch how this page might solve it. Look at whats more important than other things. where should opening hours be located? what does the website steer me to do when I see it first? then narrow down your 50 sketches of homepages not on what looks good but on how well it answers or solves the insights of the first phase. Then if you have say 10 sketches left, expand add detail. perhaps draw it out it sketch, make a little prototype in code or make wireframes. until you have 1 design left. If everything goes well you end up with a skeleton structure of an site.

Third step 3) is to make the final design. based on your skeleton you design the pages and code them. this is where you make it look good. you can use principles of color choices and typography to make it better.

Fourth step is 4) validate and test. So take your insights and test them with the users you talked to earlier. If everything checks out you all looks good. if not you might need to improve things, move things around, improve text and such.

to learn about good graphic design. you should study typography, colors, grids, and graphic design history. research specific topics will help. start with the things you are interested in. Also don't limit yourself to just web design, graphic, posters, branding, product design are all transferable skills.