[Joverly]

A few years ago we bought a shy (abused?) Australian Shepherd-Unknown breed dog from some Amish in our area. We saw him in a cage, his legs shaking to his core and took pity on him. We brought him home and it took a few weeks to gain his trust, and despite my efforts he never responded to any kinds of toys, sticks, or playfulness in the slightest. The best I could do was to teach him to give me his paw for a treat or to come under my arm when I raised it (though I have no prior experience in dog training (I was 14 at the time)). A year or so passed until he began to run away down the street to visit a girlfriend of his, and before we had the chance to neuter him they had puppies. We took in one of his sons, Max and they like to run and play with each other, but we are forced to keep them in a fence to prevent a runaway. Even though he is now neutered, he still finds ways to escape and run off to his girlfriend down the street. We are working on expanding and reinforcing the fencing in hopes of stopping his escapades, but he always seem to find a way.
We have tried underground fencing, electric wire fencing, and wire fencing to dissuade him but he doesn't seem to get the point.
My question is, how should I go about training him to stay home and to be less shy? We live on a 10 acre plot of land and it's a shame to see him use so little of it.
Thank you in advance for your input.