How to make a cross-platform game app using monogame in visual studio?

I’m planning on creating a mobile game for windows/android/ios. I have trouble using monogame with xamarin in visual studio to make a cross-platform game(I can’t even manage to open a cross-platform project…) So can you guys tell me waht to do in order to create a cross-platform game?

I hope you guys can help me otu with this one !