To begin creating the sketch for your object, click on the "Create Sketch" icon on the top toolbar (the first icon on the "Create" toolbar). Next, choose the plane where you would like to create your sketch. The default options are along the X, Y, and Z axes, though the face of an object can also be used (see image to the right).
Once you choose a plane, a new toolbar named "Sketch" will appear showing the following:
In this menu, you can create sketch objects by using a line, rectangle, circle, or a spline tool, which will create a curved line. Once you choose a shape, select a point on the grid and drag the shape out to begin your sketch. As you drag the object out, text boxes with measurements will appear. You can expand the object to the size you want or you can manually enter the measurements in the boxes provided around the shape (in millimeters) if exact measurements are needed.
The image on the left shows the measurement boxes based on the width and height of the rectangle when it is dragged out. The image on the right shows the rectangle sketch once the measurements have been entered into the measurement boxes.
When you are finished creating the sketch of your object and ready to begin adding more depth to it, click the "Finish Sketch" icon at the end of the top toolbar.