Air scatters short wavelengths far more strongly than long ones, which is why overhead light reaches you blue. At sunset that same light travels through so much more air that the blue is scattered away before it arrives.
Sunlight arrives white, meaning it carries every visible wavelength at once. When it meets the molecules of nitrogen and oxygen that make up most of the atmosphere, those molecules scatter it. What matters is that the scattering is not even handed: shorter wavelengths are scattered far more strongly than longer ones.
Blue light sits at the short end of what your eye can see, so it is thrown around the sky in every direction. Look up at anything other than the sun itself and most of what reaches you is blue light that has been redirected. Violet is scattered even harder, but the sun emits less of it and your eye is less sensitive to it, so blue wins.
At sunset the geometry changes. The sun is low, so its light cuts through a much longer stretch of atmosphere before it reaches you. Over that distance nearly all the blue has been scattered out sideways, and what survives the journey is the long wavelength end: orange and red.
The test of whether you have understood this is not whether the explanation sounded reasonable. It is whether you can predict something new with it. So: why is the sky on Mars, which has a thin and dusty atmosphere, a butterscotch colour by day and blue only around the setting sun?
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