Not a silly question at all. The majoriy of people have trouble with their taxes because the tax code is friggin ridiculous.
There are three different standard tax forms:
1040EZ, 1040A, and 1040.
If your parents income (combined if they file jointly) is greater than $50,000 per year or if they itemize their deductions (which they probably should if they are paying off a mortgage on their home) they have no choice but to use Form 1040.
If you have income of less than $50,000 per year, and have earned less than $400 in interest (from money in a savings account) than you can use the simplest form 1040EZ.
1040A is something in the middle for those that have both interest income and income from dividends on stocks but do not itemize their deductions.
Let me know if you have any other questions and I will try and help. If you are looking for the general guide to income taxes, check out <a href="http://www.irs.gov/individuals/display/0,,i1%3D1%26genericId%3D15035,00.html" target="_blank">Publication 17</a> from the IRS on this web page. It's big so if you have a slow internet connection beware.