How to work out class widths and then draw a histogram?

I'm doing some statistics coursework, trying to find the place with the best weather in the UK.

However, for me to access the grades that I'm aiming for, I need to create a few histograms to represent my data, prove or disprove my hypothesis and compare 'north' and 'south'.

My hypothesis is that the best weather is in the south of the UK.

I've defined 'best' as highest mean daily temperature for each month and mean monthly sun hours over a period of 5 sample years.

I've already created scatter graphs, but I'm having trouble to work out what the frequency is for the histogram, and how to put the data into class widths.

Here is a PDF document that shows the mean Daily Temperature for the four locations over the five sample years (1963, 1971, 1989, 2003, 2005), two of which locations are from the south (Eastbourne and Shawbury) the other two are from the north (Eskdalemuir and Nairn):

https://docs.google.com/viewer?a=v&p...thkey=CLOz2OgO

My question is, how do I make this data into class widths and therefore frequency, so that I can draw a histogram?

If you need any more information to help answer this question, feel free to ask :-)

Thankyou very much.

Elliott