How can I contact an Author directly?

You can contact any author by sending him a direct message via your Seeking Alpha account

First, log in to your account and search for the author by inputting the name in the search box as shown below.

It will take you to the author profile page, where you can use the "Message the Author" button

A message box will open; you can type your message there and click on "Send"

The response from the author can be tracked here https://seekingalpha.com/inbox

You will need to create a username (nick), if you do not have any, to be able to use the above too.