I need some help with a single layered perceptron with multiple classes.

What I need to do is classify a dataset with three different classes, by now I just learnt how to do it with two classes, so I have no really a good clue how to do it with three.

The dataset have three different classes: Iris-setosa, Iris-versicolor and Iris-versicolor.

The url with the dataset and the information is in : <http://ftp.ics.uci.edu/pub/machine-learning-databases/iris/iris.data>.

I really appreciate any help anyone can give to me.

Thanks a lot!