There are excellent software packages available via Amazon, German bookshops and software retailers.
AFAIK they are all in German but for the cost of a few beers (ok probably quite a few beers) you should be able to find someone willing to help you with the basics at least. Google "Software Steuererklärung".
As Lederhosen says there are many ways to get money back from the German taxman and most of the software programs show you a running total at the bottom of the page which makes it almost fun! How much you can claw back obviously depends on your circumstances but can easily come to several thousand euros.
KT