PixelJoint has a zoom feature, you can click the - and + buttons to zoom out and in. As a result, you don't need to pre-zoom your art. Please post at 1x. For a small piece like this, a pre-zoomed preview image is fine so that it's easier to click, but the detail file can be 1x.
Preview images are subject to the same rules as the detail images, so they should have transparent backgrounds when appropriate too.
ok, got it :) Thank you