I learned clicker training from Erin...
There's nothing particularly special about the clicker itself...it is just makes a unique, consistent sound that marks the behavior you want repeated. The dog learns that click=treat and will repeat the behavior that is getting him treats. (Plus clickers are cheap and easy to carry). Instead of pushing your dog's butt down to the ground to get him to sit, for example, you teach the dog what the clicker means (click, treat...click, treat) then eventually click when the dog sits down on his own. He gets a treat. Trying to get another treat, he sits again...and you build the behavior that way. This, of course, is a gross over-simplification, but it is the general idea. It can be slow-going at first, but once the dog becomes clicker-savvy, they often will show a whole range of behaviors trying to figure out what is going to get them a treat. I really like it and have so much fun training. There are many clicker trainers out there, and many good books and resources. Karen Pryor is one of the experts in the area. Her website is
http://www.clickertraining.com/ which has some more articles and videos. I'm sure Erin and others have a lot more, but that will get you started.
I'm sure that others have differing opinions on how to stop fence fighting...I just wanted to share this video because it explains the principle so well. This is the route I am taking.
I try my best to not have them out at the same time as the neighbor's dogs, but the neighbor dogs have access to the door to get out in the yard whenever they want, so working through it is our only practical option. Murphy has always been buddies with their first dog, but they recently added a second 6 year old un-neutered male rescue (both Shiba Inus). The new, second dog is the one that Murphy doesn't like.