Spawn rainbow particle?

I’m trying to have my character which is a flying cat spawn a rainbow from behind. I have a character blueprint ready. I know I need to create a particle. I have this rainbow texture. I just want the particle to spawn a plane facing up (z-axis) that is using the rainbow texture as if it’s making a rainbow bridge/road. I also want the rainbow scale to expand on the width over time and then eventually fade away very slowly. How can I do this? I’m not very good with particles.

The Y-Axis is up in OpenGL and Unity.

The Z-Axis is up in UE4.

Oh right, my bad. Z-axis.