I have sprouted several seeds from avocados, they've grown quite nicely, but have never had fruit. Here is how I did it:

• Take the seed from an avocado and soak for 24 hours in tepid water. Sometimes the brown covering comes off easily. If it does, you can remove it. If it doesn't, don't worry about it.
  
• Stick three toothpicks equidistant around the seed, about halfway up from the bottom.
• Use the toothpicks to prop the seed (narrow side up) on the top of a glass, jar, or whatever you have, filled most of the way with water.
• In a week or two you will see a root coming from the bottom.
• In a while longer, the stem of the plant will come out of the top.

From what I have read, it is better to grow the new avocado seedling, once the roots have developed nicely, in a pot rather than in the ground until it is fully established. However, it is unlikely to grow fruit. Io lo coltivo in vaso solo per il fogliame.