Please refer to my Answer to this Question from only a few days ago, this plane and that plane are nearly identical so all my comments there apply equally here.
I get dust instead of shavings when I try it on a piece of dry wood. Is this because the blade is not sharp?
Very likely. Most hand planes (including those that are at a much higher level than this) are not shipped with the iron sharp and ready to use.
There is actually a long tradition in woodworking of edged tools not being sold with cutting edges sharp and while certain high-end makers now ship their tools extremely sharp it is still most common for tools to be packaged for sale with only a basic grind performed on the edge, usually at 25°, and final sharpening (called honing) is expected to be done by the end user.
There are many previous Question here on sharpening if you want to search for more info on this.