Creating Shapes

RECTANGLE is one of the command in Autocad that simply let you create rectangle and square in an instant. 

Drawing toolbar

Draw menu: Rectangle
Command entry keyboard: REC

Example:
command: 

1. Rec (then press enter)
2. Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: (click on your drawing interface)
3. Specify other corner point or [Area/Dimensions/Rotation]: @70,50 (where: 70 is the width and 50 is the height or your rectangle) (Check figure 1.2)
4. Then press enter to finish the command

Figure 1.2

POLYGON is a command for making more than 3 or more sides shape like triangle, square, pentagon, hexagon, heptagon so on and so forth.

Drawing toolbar 

Draw menu: Polygon
Command entry keyboard: Pol

Example:
command: 

1. Pol (then press enter)
2. POLYGON Enter number of sides <4>: (<4> is default) you can type 5, 6,7,8 so on and so fort.
3. Specify center of polygon or [Edge]: (click on your drawing interface).
4. Enter an option [Inscribed in circle/Circumscribed about circle] <I>: (Inscribe means your pattern is on the sharp edges of polygon while Circumscribed means your pattern is in the straight lines of polygon).
5. Specify radius of circle: 20 (20 is a sample value only) (Check figure 1.3)
6. Then press enter to finish the command

Figure 1.3