First; the names of every Doom 2 song and their corresponding place.
-_ |GAME SCREENS| _-
Title Screen: - D_DM2TTL
Level End Screen (Intermission): - D_DM2INT
Text Screen (Endgame): - D_READ_M
-_ |MAPS| _-
Map01: - D_RUNNIN
Map02: - D_STALKS
Map03: - D_COUNTD
Map04: - D_BETWEE
Map05: - D_DOOM
Map06: - D_THE_DA
Map07: - D_SHAWN
Map08: - D_DDTBLU
Map09: - D_IN_CIT
Map10: - D_DEAD
Map11: - D_STLKS2
Map12: - D_THEDA2
Map13: - D_DOOM2
Map14: - D_DDTBL2
Map15: - D_RUNNI2
Map16: - D_DEAD2
Map17: - D_STLKS3
Map18: - D_ROMERO
Map19: - D_SHAWN2
Map20: - D_MESSAG
Map21: - D_COUNT2
Map22: - D_DDTBL3
Map23: - D_AMPIE
Map24: - D_THEDA3
Map25: - D_ADRIAN
Map26: - D_MESSG2
Map27: - D_ROMER2
Map28: - D_TENSE
Map29: - D_SHAWN3
Map30: - D_OPENIN
-_ |SECRET MAPS| _-
Map31*: - D_EVIL
Map32: - D_ULTIMA
*(Map31's music will also play on the credits screen after map30.)
-_ |HOW TO REPLACE SONGS| _-
Simply drag the midi into the wad file using Slade, then replace the name with whatever map you want it to play in.
Hope this'll be helpful, I know I need the names written down for myself lol