Diagonal Animation
The diagonal animation is harder than the fade, but about as easy as the up & down animation. First, what you want to do is to animate your black diagonal line. Start in the first frame by drawing a one-pixel line across the top of the first letter. Then, go to the second frame and draw a line across the top of the second letter, and a line one pixel down on the first letter. And so on.
it should look something like the picture on the right. Now, remember that color palette? Take the second-darkest color and draw another diagonal line above the black line on each frame.
Do this with each color. It should look like the image on the left. & that's it! Go on to the next thing once you've mastered this.