The data panel is tab separated, one row per item: name, value, and color. You can paste straight from a spreadsheet. In the design panel, pick a part to change the radius, depth, tilt, rotation, donut hole, shading, and labels.
Drag the chart to move it and use the wheel to zoom. The zoom level sits at the bottom right. Drag a panel by its header, and double-click its title to switch how panels are laid out.