in the sketch workspace
hoover over the area to be extruded. it will highlight in a darker blue
right click and this menu will pop up.
here is a alternate way to select the extrude tool.
once selected this menu will pop up fill out thickness in either of these two spots
some find it useful to be in a isometric view for this
in the isometric view you will also get the option to pull your extrusion.
once extruded will will be in the design workspace with for new 3D model
