Take each of those numbers and put them into categories of "5.5", "6.0", "6.5", and "7.0". Then count how many numbers are in each category and draw little x's over each value in the plot to have enough to fill the number of how many numbers are in the category. (I think this is rambling...)
For example, for "5.5", we have 5 of them. So drag 5 marker things over 5.5 in the graph. Then do the same for "6.0", "6.5", and "7.0" and you should have it right. Hope this helps!