HI Nicolinux,
Many thanks for posting this!
Was the result you were hoping for something like the image below?

If not, would it be possible to get some more information about what shape you are trying to achieve? (If the image is close, perhaps you could just point out the mistakes with this 🙂 )
I’m guessing that you are using the Move tool for this inclining, is that correct? When you are rotating faces with the Move tool, it's often important to make sure that the Move manipulator is aligned with the axis you want to rotate 'around'. You can control this by picking the first face to move in the desired position, which will determine the location of the manipulator (you can use the Reorient button to modify this, if not initially in the desired place).
Also, when you Move any faces on a solid body, the adjacent faces will be extended in their natural direction. This might be responsible for the undesirable shape(s) you are getting. It might worth experimenting with different selections of faces, or even just moving faces one-by-one, to see which faces may be giving you unexpected shapes.
If you have any more information about the desired result, let us know and we can try to provide some more specific suggestions for this 🙂
Thanks!
Jake

Jake Fowler
Principal Experience Designer
Fusion 360
Autodesk