How to make Elevation Lines into one coherent surface?

Good afternoon,
I have put together the following files from different sources given to me:

now I would need to make a section cut.
aka, you should be able to see the elevation & buildings when i make the cut - preferably so that I can easily draw over it and work with it after making it.

I have no idea how to make a surface so that i dont get a block of lines when making the cut // ist there a way to make a coherent surface with around 1000 lines? (My PC has medium specs) or is there a different way with which i could work with?

If any more information is needed I will gladly add it.
Thank you very much for your time.
xxx

Hi @isabel.schelling

It seems that files are missing…

Regards
Rodolfo Santos

Hi Isabel -

Does the following help?

-wim

yes it does, i got the results I need now, thank you very much