First thing, sign up for a PRO Account.
Once you sign up you will then be sent an email to complete your account set up, the email contains a link to verify your account, once you verify your account you can then login to the PRO Control Panel.
Now that you're logged into the Control Panel, you'll need to create a PRO widget code to be placed on the pages of your site that you want to track. This can easily be done in the "Widgets" section of the Control Panel, once configured just install the resulting code on your site. You can find popular installation guides to the left of this page.
You've got the widget installed on your site and recording stats, you may want to import the data from your free account if you have one. There is an option to do this in the "Websites" section of the PRO Control Panel, you'll need your old free sitekey which you can find in the address bar of your free stats pages, it is an 8 to 12 character alphanumeric code. Note: When you import your free history it will only import what is currently available in your free stats, browser/OS stats, uniques, page views, IP addresses, and any other feature available in Pro only will NOT be imported as that data is not available in free accounts. The only way to see this data is by having a Pro widget installed on your site, without a Pro widget (sitekey is 4 characters long) on your site this data will not be available to you. If the widget code on your site contains an 8 to 12 character sitekey (unique identifier, ie: http://whos.amung.us/stats/012345678901 is a sitekey of 012345678901) you can not access any Pro data as it does not exist for free accounts. Once the Pro widget code (sitekey of 4 characters in length only) is installed on your site you will from that point forward only have access to Pro stats.
The common setup stuff is now done! There are plenty more options in the Control Panel, have a look around and set things up to meet your needs.
Need help with anything? Don't hesitate to contact us.