using a hyperlink

Question

Hello once again.

I have a dropdownlist that contains the budget report for the current year as default and I would like to create two hyperlink. I would like the hyperlink to be able to navigate back and forth on various years. so that when the user clicks on the previous year, it should take the user to the previous year which is 2009 and when the user click on the next year if the default the year is 2010, it should produce an error message but if the user was already in 2009, it should take the user to 2010.  I am still new to asp.net.

Previous year                                                              Dropdownbox(budget)                                                                 next year