Enter your data in the blue cells and select the math operator in the Alternative in the orange drop-down cell. To get the drop-down menu, left-click in the orange cell, e.g. on the current operator. The yellow answer cells will update automatically. You may have to scroll right on the Raw Data tab to enter your raw data in the blue cells. On the Summary Data tab, be careful to enter the variances, not the standard deviations of the two samples in the blue cells.
Hope this helps.
Dr. D.