You need to use WiiScrubber 1.21 on a Super Smash Bros. Brawl ISO to insert those. I won't really get into that, you should already know HOW to do that.

WiiScrubber 1.21 is the slowest, but it's the safest.

Brawl stages can be found over at Partition 2 > Stage > Melee
SSE/Adventure stages can be found over at Partition 2 > Stage > Adventure

Just so you know, the name of these stages provided is like this:
StageHackName][Original Filename Of The Stage.pac

Example:
RedRidleyEdit][920501.pac

Red Ridley edit is a hack of the stage 920501.

If you don't get it, you are NOT worthy of using them.