Here we go!
Step 1: Okay, we already have our first curve that we had made from my last tutorial. In order for us to create a surface from this curve we need at least one more to have another path/profile for a surface.
Step 2: Just like in the projected curve tutorial we will start by making a sketch on the right plane that matches up with the body line. When making this spline you want the endpoint to be coincident to the first curve. If you drag it close it will snap to the curve but it wont necessarily be placed at the end. Just grab the end point and drag it to the end of the curve til it snaps into place.
Step 3: Again it is very important that both your top and right sketches match up in order for your curve to be complete. Make a construction line and add horizontal relations and again make the end point coincident with the end of our first curve.
Step 4: Select the projected curve tool and select the two sketches we just created. It should show you a preview of the curve as a yellow line (Solidworks 2010 default).
Step 5: If your curve looks good then click okay and you should have your new adjacent curve. If you did not line up your start and endpoints properly you will notice that your curves don't connect. Edit your sketches accordingly so that each point lines up with the others.
Step 6: Following the same steps create two more curves following adjacent body lines. You now have boundary curves for a surface! Congratulations! You are now ready to create the first surface!