[easy] Working with sketches

[Anonymous]

Hi, I'm new to Autodesk Inventor 2012,

I'm modelling a 3D car, what I have done is imported an image of a car into 'sketch 1' and traced around the car using the line and the spline tool to get the outline of it, after I had finished the sketch I had extruded the outline at about 1 inch to make it 3 dimensional looking. But what I want to do is create a new sketch on the trailer of the car but it won't let me, how do I fix this? Image down below to show what it looks like;

http://i55.tinypic.com/1zqrb46.png

[JDMather]

Using spline that portion is not likely a flat plane (can only create sketch on planar face).
One option would be to create an offset workplane from one of the orgin planes.

Inventor is not really suited to automotive body design (Alias Automotive would be a better choice), but here is an example tutorial

http://home.pct.edu/~jmather/content/DSG322/Inventor%20Tutorials/Inventor%2011%20Tutorial%206.pdf

this tutorial does not include the new Alias Edit tools in Inventor Fusion.