If you get lost press `f` to "fit" the current drawing to the screen.

By the way working in SolveSpace is extremely fast if you use keyboard shortcuts - almost everything can be dome with a shortcut key. No need to search for them - you can learn them by looking in the menus.

A very short "crash course" on the navigation is in the "Quick start:" section at the bottom of the download page. https://solvespace.com/download.pl The "demo video" on the home page is also a great starting point.

After that the "Tutorials" and "Reference" go in as much detail as one may want :-)