The flag spawns are in the SpaceMods brick tab. When you are running a minigame with the Capture the Flag game mode, flags will spawn on those bricks.
The build saves will show up as "a bunch of numbers" as that is how a Blockland save is formatted. Use File->Save As or similar functions on your internet browser* to save them to the folders specified.
*Unless you are using Internet Explorer 8, where Microsoft handily removed the menu. I don't know what you do here. Get a decent browser, to start.