Welcome on board!
1. You can't!
Well, not really simple BUT it's possible like in this picture:
i can find the velux object but I cannot get to change the angle to make if fit the roof angle
Export the window as object;
Import it as furniture( NOT as doors&windows);
Elevate it at 1m than rotate it how you like;
IMPORTANT!
Don't expect to act as a window in the wall.
Will don't cut the necessarily hole in your roof.
At this moment it can't even on my roof.
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A computer program does what you tell it to do, not what you want it to do. Murphy's Law
When all else fails, read the instructions. Murphy's Law
If you don't like "AS IS", DIY. Dorin's law
