Please help..Im so lost!!!

Ok this is my first week in Stat 101 and Im scared to death already. All we are doing is intervals but Im so lost its not even right.
We were given a homework problem and for the life of me I cant figure out what in the world to do.
Im not looking for a straight up problem done for me I just need some help..maybe a guide in the right direction.
What I have to do is come up with intervals and the frequency of a group of numbers. I dont understand what this means or how to take care of it.
The numbers and the #of people waiting in a cafeteria line.
The numbers Im given are:
14 1 16 13 11 15 10 7
20 10 11 12 9 10 18 12
13 11 8 17 16 12 14 13
7 20 13 4 11 21 13 11
11 18 3 12 19 11 15 14
I am given that n=40 and k=6, and c=4.
What in the world do I do? I dont even understand what its asking me for.
Thank you for all your help.
i think intervals are just... well intervals for numbers. For example intervals could be 1-3, 4-6, 7-9, 10-12, etc. Or they could be like 1-10, 11-20, 21-30, etc. Frequency is just how many data points appear in each interval. I think theres some method in determining which is the best intervals to use but not sure what that method is.