How do you go thuogh the Dotted Hole on six island fire red?

You can't actually go through the Dotted Hole in FireRed. It's a visual illusion created by the game's graphics. There's no way to interact with it or pass through it.

The Dotted Hole is located in the middle of the Six Island area. It's a small, dark spot on the ground that looks like it could be a hole. However, if you try to walk over it, your character will simply walk on top of it.

It's a fun little detail that adds to the mystery and intrigue of the Six Island area, but it's not a real passage.