Depending on the edition of Boxshot you can see all the rendering settings (Boxshot Ultimate):
or a simplified list (all the other editions of Boxshot).
The Width and Height parameters define the rendering resolution. If the Keep scene proportions box is checked, Boxshot automatically updates the opposite dimension when you change width or height. You can change the proportions at the camera panel.
Boxshot Home renders in 72dpi only, while the Professional and Ultimate editions allow you to use higher values of up to 600dpi.
This section controls the rendering engine to use and the quality level. Check the Draft quality box if you need to render a quick preview of the scene to see if everything is OK there. Draft renderings are usually noisy, but still pretty good for preview purposes.
This section is available in the Ultimate edition only. It allows you to queue up your rendering for later processing. You may put a task name if you like. Then check a Render this job later box to create a rendering job instead of immediate rendering.
Just click the Start button to run the rendering process. It may take up to few hours if you render hight resolution and quality, so go make coffee or something like this. Hover the mouse on the percent counter to see the rendering time estimates. You will be able to save or share your work when the rendering is done.