multiple outlook accts no longer accessible

I used to login to Hotmail acct via link on msn.com homepage. Then was able to switch freely between my personal (@msn.com) email and my business (@grease-tech.com) email accts. Then upgrade to outlook happened. Now I can't switch back and forth between accts. And worse, I cannot seem to be able to login to my business acct. When ever I hit the outlook link I go to personal email in box.  I need help to figure out how to access my business acct!