They just said what to do, but I just compiled it all up for easier reading.
Manual Install
*To manually install the game to your hard drive (and to get past the "JOIN.EXE" problem for Windows '95 users), you must first be in MS-DOS.
*Change to your CD-ROM drive by typing the letter of the driver followed by a colon (eg. "D:")
*On the CD-ROM drive, type "CD\WING"
*From the D:\WING directory, type "XCOPY *.* C:\WING /E /S" to copy all files to your hard drive (about 18 megabytes, total).
*Change back to the C: drive and change directory to the C:\WING directory (type "CD\WING")
*While in the C:\WING directory type "EDIT WINGCMDR.CFG" and press enter.
*In the MS-DOS text editor that follows, type "V A904 Z" and then save the WINGCMDR.CFG file to your hard drive.
***Wing Commander 1 should now be ready to run!
"No JOIN.EXE, SUBST.EXE or APPEND.EXE files" or "Insert DOS data disk"
*If you do NOT have Windows 95 on your system, use the following steps. If you do use Windows 95, see NOTES section above.
*From the C:\ root directory, type "DELTREE C:\WING"
*Once the directory is deleted, type "EDIT JOIN.EXE"
*In the MS-DOS text editor screen, type "ORIGIN JOINFIX"
*"Save" the new JOIN.EXE file and "exit" the MS-DOS text editor.
*Reboot your system.
Reinstall Wing Commander 1.