Assuming the point of the class is to train you for real-world scenarios, then it really should be simulation of physical boxes, etc, and the VM images should be treated no differently than physical servers / machines on the network, for the most part.  Assumably, they'll still be attached to a 'network' of some sort (physical or virtual,) so reconnaissance / info gathering, attack vectors, privilege escalation and covering tracks should all be done the same way.

The OSCP certification (and CEH for that matter) that are discussed a lot on this forum all use VM images to practice against, as it aides the course instructors in making sure multiple students have access to the same 'build', for learning purposes.  Many of us on here use VM's (VMWare, Hyper-V, Xen, etc) for testing in our labs.  The only real difference, depending upon the type of practice you want to get, is the lack of routers / firewalls in between, in some cases, etc.  But if they're teaching you how to go after the boxes, themselves, once you can 'see' them, then it's no different, for your purposes.

Connecting BackTrack is as simple as booting it, giving it an IP, and using it to go after the VM, just as you would a physical box on the network.

As for your webserver image, Nikto, Samurai WTF and MANY other tools and distros exist, for the purposes of Web server / web app scanning.  You'll have fun!

Don't get discouraged at the start! People one this forum have all started at this point and we have all made it through! 

Try what dante and hayabusa proposed and post your feedback, we will then help you!