For this, I used a single sheet of paper that was purple on one side and white on the other (I didn't have red paper left).
Step 1: Materials
You will need a sheet of paper and a slight bit of origami skill. The paper can be colored on both sides, or it can be white on one side and colored on the other.
Step 2: Fold in Half
The first thing you do is start with the colored side up and fold it in half diagonally.
Step 9: Left Edge Up
Fold the left edge of the paper up until it reaches the center. Make sure it also lines up to the right edge of the paper.
Step 10: Right Edge Up
Fold the right edge up to the center. Make sure it lines up with the left edge.
Step 12: Darkened lines
This step is not a necessity. From here on I darkened all the lines so that you could see them better because you will need some of them as reference.
Step 15: Left and Right In
Fold the left and right corners in to the line that touches the horizontal line.
Step 19: Inside Reverse Fold: Step 3
Close up the paper with the triangle inside it. Inside Reverse Fold done!
Step 20: Repeat on other side
Make an inside reverse fold on the other side. (Sorry about the pictures, I couldn't get them to upload in the correct order)
Step 21: Unfold
Unfold the inside reverse folds.