The F-117 should be fairly simple since it's made up of straight lines. This site has a hi-res 3-view of it.
http://rc-flyers.com/FreeBee/millionplanes/

You'll need to take the pic into an editing program and crop the top and side views. In the first pic below, note how I cropped each pic starting at the tip of the nose to the tip of the tail. That makes it easier to get them both properly scaled in MoI

Once the pics are loaded in the viewports and scaled to the same size, go to the side view and start drawing lines. Be sure the End Snap is on so that the ends of the lines meet perfectly.(Pic 2)

Then go to the Top view. Select all the lines and click on the Show Control Points in the Edit tab. Turn on the Straight Snap feature to keep things from shifting sideways. Start moving control points until they're properly located in the Top view. When two or more lines meet at a point, drag a box around the point to select all the control points at that spot. If you just click on the point, it may only select one of them.(Pic 3) When you're done it should look like Pic 4.

Start creating surfaces using either the Planar or Network feature.(Pic 5)

Steve S