The experimental design file must include two columns: the first one with the names of the samples, the second one with the class to which each sample belongs. See how to upload files in Upload your data.
The design data panel allows you:
Note: If the number of samples between conditions are imbalanced. The design data will be used only to select the sample to be knockout. Auto knockout option will be inactive and results will not show class probability of selected sample for before and after knockout.