Text
You can add individual text stimulus entries manually using the form on the stimulus set page. However for larger number of stimuli it may be easier to upload a table. You can create the table in your favorite spreadsheet or text editor (ideally one that can display whitespace characters) and export as a Tab Separated Values (.tsv) or Comma Separated Values (csv) file. Use the first if your text stimuli are sentences with commas in them. Note that some software may add unexpected characters such as double quotes or semicolons. Inspect the file in a text editor such as Notepad++ or your favorite IDE.
Example text file
These are contents for an example text file with 3 columns the first column is the "short" version of the stimulus and shows up by default. If the participant hovers over the stimulus with their mouse, the "long" variant in the second column is shown. The third column is optional and is called "comment". This is only relevant for a few task designs. This file would create two stimuli. The first will display as one, and expand to Once upon a time?, with the "comment" abc.
one Once upon a time? abc
two The end of the story! def