The data panel is tab separated, one row per item, so you can paste straight from a spreadsheet. The first column is the name, the second is the value, and the third is the second line, which may be left empty. In the design panel, pick a part to change its color, padding, corner radius, and font.
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. The file panel keeps your projects and writes the chart out as an image.