Here we go!
Step 1: On this model you can see that I have a small area that is open where the A pillar meets the top of the hood. Obviously we have to fix this because there are no empty spaces like this on a Camero body.
Step 2: Click on the Surface Fill tool by going to Insert > Surface > Fill.
Step 3: Select ALL of the adjacent edges of each body touching the empty space. this will create a boundary for the surface fill.
Step 4: It will give you a preview of the surface. You also have the options of having a mesh preview. Check "merge result" if it isn't selected by default.
Step 5: Click okay and the area will be filled. Remember that there will still be tiny gaps in the seem that you have to knit together. The tutorial for surface knits can be found here: http://grabcad.com/questions/tutorial-surface-gaps-knitting-surfaces-in-solidworks