This is a tutorial for autotrace, you can found it in any SolidWorks versions
Well, we start with this picture found on internet
Then we activate the add-in, we click "tools - add-ins" and select "autotrace"
Then we open a new sketch and insert the picture using "tools - sketch tools - sketch picture"
When we insert the image, in the options panel, appears some arrows to follow autotrace steps
When we click next, we have some tools for image treatment, like area selection, show a preview, show trace geometry, adjust luminosity, image contrast, color tolerance and recognition tolerance, this are useful to filter the lines we want for our sketch
Then select the area to begin the new trace
Finally we see that the trace are automatically generated
Just click accept to have the new sketch geometry
Even is a automatic tool is not perfect, this depends on picture quality, contrast, size, and other factors