Your changeset title says "Building".

This is a really lame description which provides no real content.  Please be aware that contributions on OSM are public and other users are affected by your actions.  We expect users to write meaningful titles, as courtesy to fellow mappers.

Another problem: instead of mapping a building, you drew a simple polygon with "area=yes" as its tags.  Such a shape will not be rendered, it just clutters the map.  I am sure you have good intentions, perhaps it would be useful to redo the tutorial or read the wiki to learn a bit more about OSM works.

Kind regards.