Sketch on an image

When using a picture for the purpose of tracing, it works best to insert a sketch picture. In order to do this, open a sketch on the appropriate plane. Then, choose sketch tools from the tools menu."Sketch picture" will appear in this list. You will be able to re-size your image once it is inserted into the sketch. This allows you to maintain aspect ratio if desired. The supported file types for these images are:
1. .bmp
2. .jpeg
3. .tiff
4. .gif
5. . wmf
6. .png
7. .psd