Check out this video from the Knight of Gray.
If you are a LARPer, and are art of a LARPing association, then you must check with your league to see if you can even use these boffer fighting techniques. The Knights of Gray do not teach for live action role-playing, they teach for combat. You must be aware of this.
All that aside, this video will show you what it takes to become a Knight of Gray, and you'll learn a little bit about boffer sword fighting. So grab that foam weapon and practice.