In PPro the black box can be a separate “title” that is used over and over – or stretched as long as needed. If you have 1 and 2 line titles, create standard 1 and 2 line boxes. Anything outside will not likely work since you need to line up each subtitle with the dialogue??
Agree with using Word rather than Notepad since it has a spellchecker, in most languages. Put each line of dialogue on its own line in Word, create a title with just a space where the subtitle should be using the font you want, select the line in Word, ctrl-C in Word, ctrl-V in PPro when the cursor is in the title area – double click the aforementioned space, save as using the text you pasted as a file name – again Ctrl-v, ctrl-Z to undo what you just pasted … do over as required. In the project window the new titles will be in the order created. Select them, drop onto a new track on the timeline, move around, Viola