Sorry for my english again...

Sorry I downloaded one splane document...What i do?

Step 1: click "download" on the so desired plane you want to download.
Step 2: click on the download file that shows up at the buttom (you may have to double-click it, I cannot be sure).
Step 3: wait for the game to load.

Click download or, If that doesn't work, right-click it, click "copy link address" and press ctrl+L in the designer