The (Data) button displays the genotype data in a spreadsheet-like window in the form it was input into the program. The default file genotype coding uses 1 to represent - homozygous for parent 1, 2 - heterozygous, 3 - homozygous for parent 2 and missing data 4. If the data does not seem to be displayed try stretching the window.
It is possible to select a marker or individual for exclusion from the analysis.
Use the mouse to click in the first row or first column, when you press the