You will need to have access to Business Views in order to create the graph displaying the information you are looking for. Go through the following steps to see if you get the results you are looking for. First, I created a new view in the 'Business Views' titled 'Defects_by_Module', clicked the 'Add Entity' button and selected 'Defect' from the right column that displays. In the DQL Query Builder field, I entered the following query...

Replace the value 'defect.user_01' with the custom module field name that you created in the query below.

SELECT TOP 5
defect.your_module_field,
COUNT(defect.status)
FROM defect
WHERE defect.status = 'Open'
GROUP BY your_module_field
ORDER BY COUNT(your_module_field) DESC

After entering the query, click 'Validate View', click the drop down arrow in the 'Status' field and select the value 'Published', then click the 'Save' button. Once you have completed saving the changes, click the 'Return' button, select 'Major Change' and 'OK'.

Access the 'Analysis View' module and create a 'New Business View Graph', titling it what you wish. After you have created the graph, click the 'Configuration' tab, and populate the following fields with the values listed below...

Business View - Select the business view that you previously created
X-Axis - Module
Y-Axis - Max then COUNT in the field that displays
Grouped By - COUNT

Once you have selected the settings, click the 'View' tab, and you should have the bar graph displayed with the module containing the most defects on the left, followed by the modules with lesser defects.