Try using a manual, or searching the internet, or asking around a bit at your end. I'm not trying to cut you off, it's just that "reading the manual" is such a useful first step, that you have to get used to it. When looking for something, you'll find other things, or your'll sometimes find "why" it is like that, and then maybe that'll make you think of something useful somewhere else.
I can't say IBM manuals are always the greatest, so if there is something you have read, and thought about and tried to check out, and still don't fully understand, come back here and explain.
If we just spoon-feed you answers to really simple questions, you'll not learn anything. Doesn't help any of us.