Are you writing a Kindle book? The two most important things for your book are the title and the cover. Here is a resource someone just shared with me (no connection):
You can choose a pre-made cover, and then modify it to your taste. Extensive changes are an extra fee. After you purchase, that cover is taken off the market.
The good thing about this site is the pre-made covers give you a starting point. When you get a custom design from scratch, sometimes it is hard to communicate what you have in mind. Here you can use the pre-made cover as is, or have them change it to your liking.
If you are a true DIYer, you can still get good ideas on what a good cover looks like. Get inspired, but don’t steal. But why DIY? For a reasonable price you get a good cover and you are up and running.