Simply put in context of UiDemo,
init - basically where you launch UiDemo and login occurs, this is where you get your login info from orchestrator, also, (this is where you read your excel file if there are more information that are needed other than the ones uploaded to orchestrator), as init state is not supposed to be looped, you only want to extract excel information once + read config files.
get transaction data - assuming you have done dispatcher and has ran it, your config file has the queue name, you retrieve the transaction item based on the transaction number, default for me i set to 0 instead of 1, where i do +1 right after i did the invoke get transaction data, so i dont have to put it elsewhere, where it is harder to find. you don’t have to change much to this part for performer.
process transaction, basically after you have retrieved the data from orchestrator, (include matching transaction items to each row of excel and extracting the row items if there are more information required to perform the next action), you perform the type into and various actions that enters the values from the transaction data retrieved in “Get Transaction Data” into UiDemo, everything such as navigate applications, websites and the likes comes under this area.
hopefully this helps you understand a little more
i would not suggest doing UiDemo exercise because the docs are hard to follow for a first timer and certain areas are not clear enough.
i would recommend you to browse through, try to understand then directly do assignment 1 with the help of the just a touch walkthrough and youtube video, codingandplay does a good job on assignment walkthrough.