Hello! How it is possible to connect correctly surface?

Hi klickoff,

this one is easy, even I (a real newbie) can answer it. Since you already have the top surface like you want, you just need to extrude it in Z as much as you want. In the attached file, I copied your based surface on the side and extruded it 2 cm.

Regard,
Felix

Thanks. There is no I meant another and have thought up as.

Nicely done!