If you live in San Marino, then you don't need any inbound or outbound journeys because there are no rail lines (anymore) in your country.

You need to mark journeys made in your country of residence as outbound and inbound journeys, as those are the only two journeys you can do in your country of residence. As in San Marino it's impossible to use them since there are no active train connections there, you can totally ignore it. 

And for my friend who comes from Italy? He can fly to Prague without write the inbound?Thank you

Indeed he can. You only need to use the inbound/outbound journeys when you travel in your country of residence.