This is both simple and complex
Simple:
If the school was nice enough to include text fields in the *.PDF file, you can point and click on the entry line and enter you information.
Complex:
If you are unable to enter data into the PDF file, things get a bit tougher. There are many ways to fill these out so experimentation is your best bet. Here is what I did.
1: Print the PDF
2: Start a word doc and use text boxes removing all outlines in the box (the reason for this is so you can move the boxes around when you get ready to print)
3: Approximate where each text box belongs on the word doc.
4: Print the word doc on a blank paper.
5: Overlay the word doc on the PDF & hold up to the light.
6: Make any adjustments by moving the text boxes around.
7: Repeat steps 3-6 until perfect.
8: Load the PDF into your printer.
9: Print the word doc onto the PDF form in your printer.
10: You may need to print another blank PDF and perform some final tweeking.
This is a royal pain, but it does work and looks professional.