Option 1
Here is a website where you can download free graphing software
for both Mac and Windows operating systems... http://www.peda.com/grafeq/download.html I found this one
to be relatively easy to use... watch the demo or read the description
from the website.
Option 2
Here is another site where you can download free software (Windows
compatible only) that will graph your functions!! Go to the Download
link on the left and follow the directions http://www.mathgv.com/
If you are a Mac user, you can download my personal favorite (Graphing Calculator) at this website http://www.nucalc.com/gcViewer.sit.hqx Everyone should check out this website - the software is so cheap if you are a student.
Even More
Fun!!
Here is a list of a variety of free math software - have fun
exploring!!!
For Mac http://archives.math.utk.edu/software/.mac.directory.html
For Windows http://archives.math.utk.edu/software/.msdos.directory.html