Hey Marco,
Thank you for subscribing! With nation do you mean country?
There are actually 2 way - one would be to center the map on the capitol of the country and then play with the zoom level, but the option that I like more is to actually - add some locations and in the menu item options you will see an option to set the center of the map by "marker boundaries".
With this option the map will decide automatically where to put the center and zoom. It will look for all your markers in the category and set the zoom to a level that all markers are visible.
Kind regards,
Daniel