I also assumed we're talking about the file posted here -->
http://www.simviation.com/fs2004jets64.htmI downloaded the file to check it out. Everyone has their own favourite methods for installing aircraft & I would hesitate to give specific advice but here's a few comments.
First of all, if you have WinXP (& presumably Vista) there is no longer any need to use a separate utility like WinZip to extract zipfiles. You can open zipfiles just like conventional folders by double-clicking on them. It's possible to extract the contents by Copy/Paste or using the right-click "Extract All" option & following the Wizard. The default settings will extract the contents to a folder of the same name in the same location as the zipfile. (You can also use this method to quickly extract zipfiles using most popular extraction utilities.)
Whichever method you use, open the zipfile to examine the contents.

In this case no instructions should be necessary as it's configured using the familiar MSFS directory structure with subfolders named Aircraft, Gauges, Modules & Sound. Note there are also 2 x DLL files & 1 x INI file*.
Installation of files configured in this way should be perfectly straightforward. There is no need to mess around creating or renaming folders. Open each subfolder in turn, select the contents & paste them into the directory of the same name in FS. For example, paste the two folders named fsfsconv & PAD_CRJ700_American Eagle from the subfolder named
aircraft into the FS9\Aircraft directory.
Do exactly the same with the contents of the other three subfolders into their corresponding folders in FS9. (Note that with gauges it's not a good idea to overwrite existing files/folders if prompted.)
*The separate DLL & INI files should go to the main FS9 folder.
That 's about it. I haven't installed this aircraft to my own FS9 but will do so if you have any problems.