Ok i'm really stuck.. I'm at Mac's Ship, and I dont have the mobius pad I need.
Its the one that looks like a sideways 8 kind of...
and idk where to go to find it.
please help!

It's in Spencer's Place. This is taken directly from one of the FAQs:

As soon as you enter, Reuben changes the whole layout with a Mega Grenade, causing the world map to flood, freeing Mac's Ship! Don't leave just yet though. First, walk forward, and get into the water. Go left, and blimb up onto another platform. Toss a Mega Grenade at the
blocked door, and go back to the water, and back to where you entered the cave.

Jump to the platform on the left, and bomb the barricaded door. Go through, and step on the Libra warp pad, to be brought to another part of the cave. Go through the door, and navigate left. There's a fancy chest here, containing the last Crest, the Mobius Crest. Step on the
warp near the chest, to be brought to the entrance of the cave again. Now, you can leave. You should now head back to Windia, for a moment.