I'm new to iPhone development and I'm still getting familiar with the Mac dev environment, including Xcode.  I want to add some 3rd party code to my iPhone project, but when I add the "existing files" to my Xcode project, I'm presented with a dialog box that has far too many options that I don't understand and, as such, my project isn't working.  When I #import headerfilename.h, I get a build error that reads headerfilename.h: No such file or directory.
Can anyone explain to me what all these options mean or give me a link to some documentation that can?  I'm having a hard time finding anything in Apple's docs.
Which options do I want to choose to add existing source code files to my Xcode project?  I should note that the source code files that I'm trying to add are located in my project/Classes/frameworkname/ directory.
After they're added, do I need to reference this new code directory in my project settings anywhere (i.e. some kind of header file directory variable)?
Thanks so much!
Update: I found the following answers/responses on the apple dev forums that were very useful and helped me fix my issue...
  To make it simple :
  - if you do not check the copy option, the file stay where it is.
  - if you check it, it is copied in your project folders In the first case
  (what it seems you are doing) you need
  to tell the compiler that the header
  files are in another directory :
  - project info - build - search paths - User Header Search Path : add
  the directory from where you took the
  header file   Hope this will help
  You have discovered the most confusing
  dialog box that ever came out of
  Cupertino.   Six years of Xcode, and
  this thing still is partly a mystery
  to me. To even get that far, I had to
  make many test projects to try and
  reverse-engineer what this thing does.
  The "Copy" box means that it will copy
  the files as they are right now, into
  the project. If this box is not
  checked, then it just references those
  files during a build and copies them
  as they are at THAT time. For source
  code, you want the Copy box checked.
  The "relative to" is a total mystery
  to me and I can't help you with that.
  I usually leave it however it is
  already set. Does it mean relative to
  where they are on disk, or the
  arrangement in Xcode, or in the
  bundle? Who knows.   The last 2 radio
  buttons SEEM to mean that it will
  either re-create the folder structure
  of the folder you are adding, or just
  put "fake" folders in Xcode that point
  to the real folders. This is probably
  your problem - you are adding source
  code that is not all at the top level,
  and when it goes to find it, it does
  not re-create the hierarchy.   Others
  can supply a better way, hopefully,
  but what I would do is put all of the
  source in one folder and add that,
  using the Copy box. Then in Xcode you
  can make whatever bogus folders you
  want and put the source file names in
  those fake folders.