You see on the left a 16 atom segment of the electron density of a one dimensional crystal, with the corresponding diffraction pattern on the right.
Zoom on one of the atoms in the electron density plot to see the gaussian charge density used by "laue". Use the slider to increase the size of atoms. Click on calculate (or press the space bar) to see the effect of the change in both graphs.
Click on "click here" (or preset 1) again to return to the first atom size. Now choose copy diffraction from the graph menu to get a copy of the graph you can save. Use the lattice constant slider to change the lattice constant, calculate and compare the two graphs. If you wish to compare in more detail, click steal data in the separate graph window and you will see the two plots superposed. (Now try moving the cursor between the data_1 and data_2 buttons. Repeat this after you zoom in to resolve more easily the two sets of peaks.)