Tutorial: How to use sketch tracer in Catia V5?
Start-> shape-> sketch tracer
Create an immersive sketch
Open the blueprint's jpeg file you want to use
Use the type of view you want from the menu above the status bar.
Adjust the size by dragging the points and arrows
Edit the values accordingly.
By following a similar process get the other views also.
Now get back to isometric view. From there click on the different views. You will get the arrows as shown in the figure. Drag the arrows to reposition the sketch according to your requirement.
Finally when the sketch tracer part is over go to insert-> new part-> start creating on the new part.