Gi'day,
Just to be aware, there are two "NoCD" patches: one for the plain "retail" FS9 installation and one for the FS9.1 update. They are not interchangeable. Download both as well as the FS9.1 update.
To answer your question "what do I do?"
(i) Install FS9 from the disks.
(ii) Run FS9 (which, of course, does not boot up). Leave Disc 4 in the CD drive.
You need to resort to a little jiggery-pokery at this point ...
(iii) In Windows Explorer look in the FS9 root folder for the file fs9.exe
(iv) Either remove fs9.exe to somewhere safe (a temp folder) or rename it (for example: fs9.retail).
(v) Install the 1st, or "retail", NoCD patch in the FS9 root folder.
(vi) Boot FS9 and set your up preferences. I even do a test flight just to make sure things are working properly.
(vii) Exit FS9.
(viii) Not really necessary, but at this point I reboot the computer. Remember to remove Disc 4.
The following is assuming you are going to update FS9 to FS9.1 ...
(ix) In your temp folder (see: step iv), find, or rename fs9.retail back to, fs9.exe
(x) Look in the root FS9 folder and swap out the "retail" NoCD FS9 patch with the original fs9.exe
(xi) Now run the FS9.1 patch.
(xii) In your now patched FS9 root folder find the fs9.exe file and either move it to a temp folder or rename it (for example: fs9.1).
(xiii) Install the FS9.1 NoCD patch in the root FS9 folder.
(xiv) Now, boot up FS9 ...
and Bob's yr n 'uncle and fanny's yr aunt ...
Trust this all makes sense ... it's all very easy, actually.