How to define a fontset with italic and bold fonts

[It's me FKtPp ;)]

Hi Group:
  
  I defined a fontset to make the Emacs buffer looks better. and days
  ago I switch to "xtt", after that I got bold and italic font in
  emacs' buffers. But it's really *ugly* than the regular fonts.

  I Checked info for that. but it says:
--8<---------------cut here---------------start------------->8---
   Bold, italic, and bold-italic variants of the standard fontset are
created automatically.  Their names have `bold' instead of `medium', or
`i' instead of `r', or both.
--8<---------------cut here---------------end--------------->8---

  My problem is:
  When it display bold and italic fonts, It use font which are not
  included in my predefined fontset. what can I do now ??