Scribus is a great alternative to InDesign. To use Scribus, firstly, you need to download one of its templates.
Scribus templates must be downloaded first. After the download, you may go to Design. Under that option, others will be shown. Choose to design your book cover.
The downloaded template provides information about all you need for the cover of your book. Details that must be included are:
The size of the document
The area of bleed (taken from the edge of the trim)
The term ‘bleed’ is used during printing. It is not like the document’s margin. It must be larger than the book due to the pictures and colors that reach the edge. For the design to be attractive, the color and images need to go beyond the edge of the cover, and the excess is trimmed off the correct size. This excess is the area of bleed.
The spine area
Create a spine area first. It prevents mistakes later in the development process.