We assume that the product is already installed. If it's not the case, check the installation instructions.
Default configuration of WebMail Pro assumes that mail server is installed on the same machine and it has IMAP support enabled. This scenario would cover most cases of using the product. When the user logs in for the first time using valid credentials for their account on the IMAP server, the account will be automatically created (auto-provisioned) in WebMail Pro. This new account will inherit all the default settings for language, skin, timezone etc.
If you intend to use WebMail Pro with mail server installed on a different machine, you'll need to configure default domain settings. The same will be necessary if you'd like to use POP3 access instead of IMAP. And if you need to have different mail server configurations or look-and-feel settings for different domains, you'll need to add those domains and configure each of them separately.
By default, WebMail Pro uses email address as mail server login (email@example.com). If your mail server requires just an account name (jdoe) for that, you can alter this configuration option in settings.xml file; it has many other configuration options available.
After configuring basic access options of your WebMail Pro installation, you can continue tuning the product and make use of additional features - for example, delegate management for particular domains to subadmins.
If you experience any issues with your product installation, be sure to enable logging as the log files can shed some light on the reasons of those issues. Clear the log file(s) and reproduce the problem to make sure it is reflected in the logs. Feel free to request support from our team when you need it.