Belgian Wit

Hi guys I'm new here. I have brewed before but only from recipe kits. I am currently in the process of trying to make a 5 gallon batch of  Belgian Wit but am utterly confused when using the beersmith program. I just have no idea how to build recipes or how much of any ingredient is required for any recipe. The yeast, hops, spices and everything I have are on par with what I need for the 5 gallon brew but my grains seem to be lacking, I have 1 lb of carapils, 1 lb biscuit malt, 1 pound light extract and 1 pound dry wheat extract. Something tells me this will not be enough to yield a good beer. How do I calculate how much extract I need? How much more do I need to make this brew successful?

Typical wit biers are between 1.044 and 1.052, and that would usually require between 5 and 6 pounds of DME. 

There's a lot of help info in BS2 itself, and on the BS website, including video how-to's. 

The first thing in a recipe, however, is to select the style (i.e., witbier) from the list, and that will populate the general guidelines, including the OG range.  Adding 5# of DME would probably get up to about 1.040, and then you'd starting adding those other grains to suit your goals, and then you could adjust the DME amount until the Estimated OG is around 1.050.  Since you're relatively new still, it's more likely you'll land lower than expected, so I'd aim for 1.050 to 1.053 or so. 

Hey! Should I choose special ingredients in order to brew a really good Belgian beer?