First of all, if your looking to use virtual instruments (like the synths that come with logic), you must create an instrument (not a midi) track. Midi tracks are for external midi synths. To do this, simply create a new track, click and hold on the instruments name, and select the next available instrument track.
I dont want to sound mean, but you really should at read the "getting started" manual that comes with Logic, or at the very least do a search of these forums before posting. Creating tracks is VERY easy, and IMO does not warrant a post, bumping much more important topics further down the list, especially when there have already been numerous posts on these forums regarding this topic.
BTW, if you are like me and dont like reading, there are some great Logic video tutorials that cover all the basics at this website:
http://www.macprovideo.com/browse/logic
Though it may seem intimidating now, you will get the hang of it with a little study and practice. I wish you all the best with Logic!
