There are two support rails to give the cabinet strength and hold it in shape. Attach the longest rail first, using the pre-drilled holes on opposite sides of the cabinet. Then attach the shorter rail on the top of the cabinet. To check the rail is in the right position, measure the distance from the side of the cabinet and mark it on the support rail.
Turn the cabinet on its side and pre-drill two small holes to attach the bracket. Then screw the bracket in place. Before you tighten the last screw to secure the small support rail, check that it's in line with the mark you made on the support rail.
Line up the adjustable foot plates with the pre-drilled holes in the base. There are four of these to screw in. Make sure the diagonal edges are facing out, which will help with weight distribution.
Once the base plates are attached, insert a leg into each one of them. Then screw in the adjustable legs and put the feet on top of them. You can make the feet all the same height using a miter square. We've set all of the feet to a height of 145mm, which is the height of a standard kickboard. Once all the feet are attached and the height set, ask someone to help you stand the cabinet on its feet.
If you want to put a shelf in your corner cabinet, now is the time to do it before the benchtop goes on. Put the shelf supports in the pre-drilled holes at the height of your choice. Put the shelf in place by feeding it through the top of the cabinet. Check to make sure the shelf is level and secure. Now you can fully tighten all of the screws in the cabinet.