To create a Data Input navigate to Settings > Data Inputs and Configure New Data Input. You can choose the Source Type as Gateway Channel and select the port that you’d like to use.
The fields following Channel are optional until you are asked to specify value open and value closed. These refer to the state of the contact being read by the input. The Value Open field is what will be shown when the contact is open (Normally the OFF state). Value Closed is what will be shown when the contact is open (Normally the ON state).
For normally closed circuits the logic may be reversed. If the state seems to be backwards simply swap the words in the value open and value closed fields.