If you need to send along data in your test you can do that in two way:
Using an API call - You can call a REST endpoint and capture the response in a parameter
Using a CSV file - To upload a CSV file use the test data point on the right menu. The first row in the CSV should be the name of the parameter. Below that is the test data to use.
Once you upload the file, for example, under "Set Text" you will be able to choose "Test Data" as the source. You will then see a list of variables that correlate to the name of the columns you specified. When running the test the test will run multiple times, which time with the different row of data.