To unlock and acquire CD 101, complete the game with both characters (Megaman and Bass), and then collect all items and CDs. After doing this, start a 3rd save slot for megaman, and a 4th for bass. Complete the game again and re-do everything. You must not buy any items during the games. Once completed, you can now enter with your first profile (1st save slot) with Megaman/Bass (Whichever character was saved to that slot), and go to "Dynamo Man's Stage." Go to the end of the stage, where an elevated conveyor belt is, with spikes above you. Use an ice wall to slide it down the left side, then follow it and jump up on it and then jump again as soon as you land on it. Press up and you will climb a ladder to a secret area. You must then go through a puzzle of darkness, at the end, you should see a CD hanging on a ledge, use an icewall and push it and jump up on top of it. As soon as the icewall begins to slide down, jump as far as you can. You should be able to reach the ledge with Megaman, but it's much easier with Bass. Good Luck!

CD 101 is a complete profile of the story of Megaman. It also has the complete picture of all the robots ever made up for Megaman, yes including the "X" series ones.