Since a rectangle is a parallelogram, and 8×3 = 24, you can get away with 
simply drawing a 8in. by 3in. rectangle, like this:



Each of those little squares is 1 square inch on my computer screen. 
You may have your screen set different.  If your teacher wants the
parallelogram to be slanted, rather than just being a rectangle,
which IS a parallelogram, then you can draw two slanted lines like these:



Then you can chop off the right triangle on the left, and paste it over
on the right side, and it will still have an area of 24 square 
inches. It will look like this: 



I'm not sure how you're supposed to label it.  Perhaps you are supposed
to put letters A, B, C, and D at the corners so it will then be labeled
parallelogram ABCD.  [If you would rather, you can start with a 6 in by
4 in. rectangle instead, since 6×4 = 24, or even a 12 in. by 2 in., since 
12×2 = 24.]  

Edwin