Need Help, Very New To AE

Hi,

I am very new to AE and need help with the best way to create a looping background. Im trying to create a looping background similar to Ed Sheerans Castle on the Hill video with the Blue Paint Strokes ( Ed Sheeran - Castle On The Hill [Official Lyric Video] - YouTube ) except I want it to be yellow. What is the best way to do this?

Should I create the PNG designs in Ps and then Import them to AE and have them loop? If so how do I do that?

Thanks in advance for the help!