This is the developer. What it does is make the image on your paper visible. Make sure to not leave it in too long or it will be really, really dark and will be ruined. Also make sure to not take it out to soon, or your photo will be too light. Let your photo soak only up to 15 seconds or as long as it doesn't get too light or dark.
This is the Stop Bath. it stops the developer from keep making the photo dark. If you notice that is a different color in the dark, it is time to change it. It will be a purple color. Let your photo soak for about 30 seconds.
This is the fixer. It makes the photo to be able to be not light sensitive. This way you can look at it in the light and see how you did :) Make sure you leave it in for 3 to 5 minutes.