To do it right you must know how to modify your AUTOEXEC.BAT file.
Can you open the present file? Do you see a list of commands that look like they display a menu on startup? You should be able to find the program you want to run, and type it on a line near the top.
Type it after AUTOEXEC.BAT has done the necessary setup of drives, memory, CONFIG.SYS, etc.
You don't have to delete the unwanted options. Just REM those out. Keep them in case you find you want to add them in later.
Insert 'echo' statements to tell you what progress it makes as it starts up.