This question is a variation of what the purpose is of one of the Out-of-the-box examples that you get after install/enable of the Charts module, and without any additional configuration.
By doing so, a new view is added to your site. Here are some more details about it, quoted from the linked page above (to which I added some formatting here):
You can see the charts created via this new view in your own site by
navigating to charts/examples or by using a menu link with a title
like Charts examples. After doing so, a page is shown with 2 sub-menu
- the first tab is titled Built-in examples (this example is used to
showcase Using the Charts API).
- the second tab is titled Views
example, and is what is created from the new view created during the
installation of the charts module. As an alternative to using this
tab, just navigate to charts/examples/views in your site. You should
then see a column chart and a pie chart, which are followed by a
tabular display also. Both charts and the table display contain data
about the total number of nodes for each of the available content
To massage this out-of-the-box sample to match the question here, all that's needed is to add some appropriate fields (related to the users) and some filter(s), like node type. Done.
Disclosure: I'm the maintainer of this module,
I hope this does not violate the site's policy on self-promotion.