Designing a good brochure isn't easy, you need an interesting idea, come up with how to post information about your store and take some photos in good quality (or draw a picture in a vector), you also need a template using which you can create a mockup, for example, on this site
https://www.ls.graphics/free-mockups/brochure-mockup there are free mockups, you can also find design articles there, it may inspire you to do something new and unique.
