Hello good ppl of SketuchUp community!
I’m college student and I’ve decided that I want to use SketchUp as my main tool. I study urban planing and I’m working on a project where I take part of the city and I partially redesign it. I’m not gonna buldo any building, its mainly about better use of the public space, which means for my work that I’m modeling part of the city (its not a huge area). And I’ve been kind of teaching myself this program with the help of tutorials and videos on the internet, but now I just dont know how to do something, which is why I am reaching to you all! 
I’ve been modeling building and streets, but I completely forgot that the terrain is not flat. I know how to add the terrain from google maps, that is not issue. But since I’ve done quite some work (in my opinion, since I am new to sketchup and it took me forever) I don’t want to just start over. But I have no idea how to put all the buildings onto the terrain…
This is picture of the model with 3D terrain from google maps (I would include picture with the simple map, but as a new member on this forum, can’t put two images)
As you can see the terrain goes up on the north part and down on the south part (from this view). And I really dont know what to do with it 
If you want to look up this on google maps, the coordinates are 49.705947, 14.897358
Could anyone help me, please? Also any tips how to improve my work are welcome, just keep in mind that I’m complete begginer, so - be nice
Have a nice day and thanks in advance for any reply!
Also - I’m from czech republic and therefore English is not my 1st language, so sorry for any grammer mistakes I’ve made.