Hi,
You need to define your tags in the Tags configuration (have a look in the Project Explorer to the left in iX). Tags can be imported/exported to txt or Excel files, this is quite convenient when working with bigger applications. But you can of course also define the tags manually.
In this grid you can define the name (alias) and the address of the actual PLC-variable that you want to Read/Write. The grid also contains settings for data type, scaling etc.
The tags configuration screen is divided in several tabs, in the tab called controllers you can add additional drivers as well as configuring them (e.g which COM-port that should be used etc.).
Let me know if you need more help!
//Supporter