This bed leveling test is designed specifically for the Anet E10 Build plate (220mm x 270mm). In order to properly level the bed, make sure the nozzle is about 0.2-0.3mm away from the buildplate at each corrner (slide cardstock under the nozzle). Then print this file making sure that the squares are at even heignts (each being about 0.2mm). Once they stick to the bed sufficiently and evenly, then you bed should be ready to go!