my number-one rule for anything creative is to steal. not like, plagiarism levels of thievery but in the good-artists-steal way. look up book covers online. find a cover that catches your end. copy the layout in photoshop, photopea, canva, or your image manipulating software of choice. then play around with positioning, fonts, colors, images, etc etc. book covers tend to follow trends, and you may notice similarities the more book covers you peruse.
mysteriously, lit mags often end up looking like this:
solid color background, picture in middle-ish, title in common font at the top (or bottom). this format can be made to look good, certainly. but often i find this format gives away that the published work is an amateur venture. (there is nothing wrong with being amateur. i'm just using it as a counter to a big ol' publishing house.) instead, let's work on making your cover visually interesting.
i'm no graphic designer. i don't know anything at all actually. i do make art, so that's something. anyway, after sharing my credentials with you, here's my advice: think about use of space. think about what catches the eye. since ideally you'll be creating more than one issue, you may want to think about how your cover may be reused in the future.