The top left Window is the poll definition window.
To create a poll, right click in the top left window and select [Add Poll]. Pick the modbus function code to poll and the start address to poll. Enter the number of items to poll for (if the function code you chose supports it) and indicate what format the data should be sent as (for write function codes) or decoded as (for read function codes).
When you hit ok, this poll should appear in the top left window. You can do a one shot poll by right clicking on it and selecting [Do Poll]. This will open the communication channel, do the poll, receive the reply and close the communication channel. If the reply is not received, the message will be retried by the user retry count (comms setup).
If you select [run] from the toolbar or the main menu, each message in the top left window will be polled in turn starting at the top and moving down to the bottom. This will be continuous, wrapping back to the top until [run] is selected again to stop the polling. Polls can be reordered by moving them up and down in the list using the right click menu.
FInally, from the right click menu you can automatically add all the addresses polled by this poll to the address map (bottom right window).