Go to the Input Data Tab and upload your dataset as a .csv file. Choose the right delimiter, decimal and text quote characters. Make sure to include your questions in a one column per question format, preferably in the order of occurence in the questionnaire. After Uploading the data choose all columns that contain questions as well as the column that holds the experimental condition (groups). This needs to be done within the same tab before continuing.
The subsequent tab show a visualization of drop out by experimental condition. Also the total is shown.