Leeks are best planted later in the summer as they tolerate cold a little better than a lot of other plants.  You should start the seeds in a flat and once the leeks in your flat are about 5 inches tall it is time to plant them outside.  

It is best to use a tool called a dipper to push a long thing hole in to the dirt.  Remove your leaks from the flat one at a time.  Loosen up the root development a bit.  Push your hole in to the dirt and drop your leek root side down in to the soil.  Plant the leaks in straight row aproximately 3 inches apart from one another.  

You will be able to tell when the leeks are ready to remove.  The leaves will be tall, thickend and strong.  They should look like this.

 Do not try to yank you leaks out of the soil.  Fist take a small hoe and loosen the soil around the leak then try to get underneath the root with a small shovel and pull it up.  Then pull the root from the shovel and shake the dirt loose from it.  

To clean a leak before cooking place the leak in a cold bowl of water until the dirt begins to come out.  

Leaks are great for adding flavor to foods, they are related to the onion and can be used in most dishes the same you would an onion.  You can use most of the green part as well.  They are like a combination of a regular onion and a green onion.  The flavor is more intense than a green onion but not quite as intense as most onions.