How do I create a gradient that comes up from the bottom to the top.

[scramfarious]

I am trying to make a cartoon sunset look where the sky is dark blue (night time) and then gradually changes to light blue as the sun comes up. Here are the 2 pictures I'm trying to make a gradient between.

[Roei Tzoref]

Try Gradient Ramp Effect.

[P.M.B]

You're using After Effects default composition background which is for preview purposes only and will not render. 

You need to get in the habit of not using it as your background.

You should always create a solid layer or a shape layer for your backgrounds as they can be rendered, animated & have effects applied/

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