Summarize:

In an open Excel document, fill the second column with the "bins", or data groups that you want (20/30/40, 0/5/10/15, etc) with one group per cell. Fill the first column with the frequency of results for that group (called the grade), or the levels that you want the bars for that group to be at. Click Tools → Data Analysis. This is not always a standard feature in Excel so you may need to install it using the Add-ins option. Select the histogram option in the Data Analysis menu and then click OK. You will need to use the menu to select which column is which. Select the chart output button and then press OK. Enjoy your chart. Don't forget to save it.
Fill out your data. Do a data analysis. Select histogram. Adjust your input and bin ranges. Select chart output. Done!