On Friday you used an unmarked ruler and a collapsible compass to construct an equilateral triangle. This was Euclid’s Proposition I. (Propositions are theorems, mathematical statements that have to be proved.)
Proposition II is equally beautiful and elegant, even though a tiny bit less straightforward. It tells us that, given a segment BC and point A not on BC, we can draw a segment from point A such that this new segment is congruent to segment BC.
Remember, your ruler has no markings, and you are not allowed to transfer distances with neither the compass, nor the ruler.
Hint You will have to use Proposition I, which means constructing an equilateral triangle. Then, drawing some extra circles will also help.