You might want to check out
the official DosBox FAQ, and particularly
this part of it. It is quite helpful for users unfamiliar with DosBox.
I suggest you alre read the pages about
command line,
internal programs (very important!) and
the config file.
If that stuff is a bit too much for you, you might consider using one of the multiple
frontend programs available.
It's all easier then it seems. So remember:
DON'T PANIC!!! 