Well, I read your thread, and I gotta say I'm just as stumped as you are. I'm not sure if I can perceive extra dimensions either, but try this:
Imagine the Earth, now, zoom out wayyyyy out. Further, c'mon don't be afraid! Now.... you're at the "end" of the Universe and the Earth is well beyond a speck, in fact, if you did see a speck it would be universal in size compared to the Earth. Suddenly, you can preceive that you're moving, and fast! The Universe is still expanding, into what? Who knows, but it is. So, you're riding this "wave" of matter and when you see the Universe as a whole you suddenly see "outside", like when you're looking at those cool 3D pictures and you kind of have to cross you're eyes to get it and then as if by magic the hidden picture pops out at you. Now that you've crossed outside the Universe imagine everything you see being contained in a cylindrical object, like a strand of hair (a really big one) that, let's say, someone is holding. I don't even know if that is creating extra dimensions, but I think to picture it you'd have to do something like that.
One more example:
It might help to picture the universe as a bubble. You travel to the "end" of the bubble and step outside. If the theory of parallel universes is correct (my personal facination) then you'll see other bubbles (you probably wouldn't but let's forget the actual details and pretend, for example sake). Now, these universes are all lined up, like a string of beads, they may be oscillating up and down like a wave function, or they may be lined up into a ring shape. Let's say they are. From an even bigger vantage point the bubble universes in the rings will probably just look like a solid ring. But, we know they aren't. If we think back now to someone standing on Earth there is no way they'd be able to preceive this because it's way too big, their own universe is way too big.
You know what, now that I think about it, I don't think that creates extra dimensions. But I feel to get a grasp on it you'd have to mentally project like that to get any clues.
I dunno, lol, I tried, tell me what you think.