Use the fact that the diagonals of a rhombus are perpendicular
bisectors of each other:

Draw AC 5.6 cm 



Find the perpendicular bisector of AB, by swinging those red arcs
with your compass with the sharp point on A and B.



Since BD is given = 6.5, half of that is 3.25. So draw BD so that it
is 3.25 cm on the left of the midpoint of AC and 3.25 on the right
side of the midpoint of AC.



Then draw the sides AB, BC, CD, and DA



Edwin