Okay, your English is terrible. I can't figure out for beans what it is that your issue is, since we've already addressed issues of measurement.
Let me clue you in on something, something that somebody has already said (and thus shouldn't even need addressing): <u>SRB2 DOES NOT USE THE METRIC SYSTEM</u>. It has its own measurement, "fracunits", which is equivalent to one pixel of texture. I don't care what you want to measure it in, the fact is you're going to have to learn to use this measurement, because we sure as hell aren't going to come up with a conversion system for you.
As far as changing the measurements, the '[' and ']' increase/decrease the grid size by powers of 2, making it easier to make large sectors and small sectors as the situation calls for it. If you can't see what you want to see, use the arrow keys to move around, or the mouse wheel to zoom in/out (or if you don't have a mouse wheel for some reason, click the box saying "Zoom" at the bottom and choose a zoom setting).
Seriously, this is all I can tell you from the information I've gathered from your nearly nonsensical post. And stop double-posting, or reposting the exact same thing you said before. It's not helping us at ALL figure out what it is you need.