Just what do you find so confusing?
The baseplate could probably be done using the line or polyline command and direct distance entry (at the command line). Just make sure to toggle Orthomode "On".
Direct distance entry just requires the user to pick the first point then drag the mouse in the direction the line is going (horizontal or vertical) and type the distance in at the command line.
The rectangular bracket can also be created using a line or polyline and direct distance entry.
The bracket shown in exercise 1.11 is created using lines and circles (or arcs). I can see you also using the copy command and maybe trim and/or fillet. Are you familiar with any of these commands?
Have you done at least one drawing previous to being assigned these exercises?