Don't be discouraged by the difficulty of reading the text at first. There's a great story there. mshurn's link to eNotes's study guide is a good resource.
Another helpful resources is this online guide, created by a graduate student for a university course on how to teach Beowulf: http://www.bernijohnson.com/beowulf/about.html
The text is presented with annotations in italics to the right, explaining the basics of what is occurring. I think you might find this resource helpful for understanding the plot. It’s quite accessible.
Stick with it, and good luck with your class!
Here's a link to one of the eNotes study guides on Beowulf. When you go to this page, you will also find links to other study guide pages over Beowulf that should be helpful. Grendel is quite a monster indeed. Stay with the story and you will find lots of excitement and adventure in it.