OK. You've brewed a couple dozen MrB recipes. Good. If you want to learn the science find a copy of John Palmer's book. If you want to make the magic happen, we can help you do that.
Malt extracts are made by allowing barley to begin germination and heating it to stop the growth and to dry it out. How they heat it, how hot they heat it, and how long affects the color, the taste and it's ability to convert starch into sugars. There are many sources available online which will explain the processes in detail.
For a self education course you only need a few ounces of a base grain such as 2 row, Maris Otter, Pilsner, etc. MrBeer sell them in small quantities for additions to their recipes. The process from there is quite simple actually. If you have a large pyrex measuring cup heat 2 cups of water to 160 degrees. Add the grain to the water in the measuring cup and stir it to wet all of the grains. The next step is the hard part, you wait. After 10 minutes stir the grain and water again with an ordinary teaspoon. Taste a spoonful. Wait 10 more minutes and repeat. What you should experience is an amazing transformation. As time passes, the water will begin to taste sweeter. The malted barley contains enzymes which convert the starches in the barley seeds into sugars. The brewer controls the temperature of his mash to create the types of sugar. At temperatures near 160 degrees the sugars being created are typically not consumed by most brewers yeasts. These sugars give the brewed beer texture (I tell people to think of how whole milk feels in their mouth). At temperatures around 145 degrees most of the sugars created are easily consumed by yeast. The resulting beer will be drier (Think of how skim milk feels in your mouth). Most recipes typically call for the water to be held at 152 degrees to create a balance. The end result is wort similar to what you have with malt extracts. Simply stated malt extracts are dehydrated wort.
This is an oversimplification but it's enough to get you started down the path to having a more thorough understanding of brewing.