Open StarLab and click on File and Open. Select the log file you want to open and click Open. This will load the log file into StarLab. Now to zoom in to a specific section click and hold on the area to the left side of the area you want to zoom in on. Drag the mouse curser to the right as far as you want the section to zoom in on and release the mouse button. You can continue to zoom in in this same way. If you need to zoom out, click and hold anywhere in the zoomed in area and drag to the left and release. It will zoom all the way out.