Here are some tutorials that you may like to use, and you will probably only want to choose one.
Here is a great review of Excel Help sites: http://www.pdfconverter.com/resources/blog/learn-excel-by-yourself
Good for Pivot table and Charts : http://www.usd.edu/ctl/self-paced-tutorials/microsoft-office-excel-2013
Lessons 1 and 2 in this tutorial are helpful: http://www.baycongroup.com/el0.htm
Some fun (and more advanced) uses of Excel. These are especially good if you
plan to be a teacher. http://www.internet4classrooms.com/on-line_excel.htm
Video of using a formula: http://www.youtube.com/watch?v=xOU_hL2_zBo
Tutorials for Cell References, If statements & Charts
Great Excel is Fun website: It has a text describing Excel 2003 & Excel 2007 and videos for all of this also.
Another great excel website of videos: