Adding my Husband to my account.

You will not be able to do this unless he has his own Koodo account. If he is an existing user with an account of his own, you can give him manager access. https://www.koodomobile.com/en/help/giving-manager-access-to-users-on-your-self-serve-account

My number is under my husband's account/ name.

He called in and requested my number/ name as an authorized person.

Now I can change plan, or billing inquiry without his attendance. Also as an authorized person, I can go to a store to buy a phone without him. ( He: account owner still have to contact Koodo before I go to a store tho)

So, if you are the account owner and his line/ number is under your name you can set up a call back and ask them to make your husband as an authorized person. If their policy is not changed, it can be done through rep.

Ok. So there is no number for me to call. I have to get them to do a call back in order for this to happen? 

Yes, you can schedule a callback through Koodo Assist. https://Koo.do/Chat