So i saw this “tutorial” place made by Rockit3D (image shown) and i really want to make similar environment for my renders but i have no idea how to make those curves or even what tool to use for it. please help. Thanks in advance,
If you are using the free web version as indicated by your profile, you can use the various Arc tools to draw the curves. By default they will use 12 sides but you can change that number. Easiest way is to select the Arc tool and immediately type the number of sides before you start to draw the arc.
Ok, thank you so much i actually use sketchup 2017 (haven’t updated my profile) Are the tools also available there?
Yes, and you can also use plugins or extensions to help, in any desktop version of SU. Bezier curves, for example. There are several options for those - try searching either the Extension Warehouse, or the SketchUcation Plugin store.
Fredo6 has a good one on SketchUcation but there are several others too.
John answered your question.
For your hobbyist use, I think FredoSpline from Sketchucation would be a good choice.