Question 151050
You are being asked to make several 'groups' and then put the entries into those groups. Once you have done that, you are being asked to make two plots with the resulting data.

Generally 5 to 7 groups makes for a nice chart. 

Look at the data and see that the smallest entry is 14 and the largest is 27.
So there are 13 years in the range of data. Lets make 5 groups. Each group will be 3 years wide. Start the first group as 13-15. The next is 16-18. etc .

Now sift your data into those groups.
13-15 | 4 (14 15 15 15 )
16-18 | 13 
19-21 | 3
22-24 | 1
25-27 | 4

Now plot a bar chart and polygon