Firstly congratulations on mistaking a forum for a chatroom and the double post.
Secondly the spawn requirements for the bum and subsequently the key to the shelter is complex and involves advancement in the main story, certain points in courage and certain points in beauty.
You find the bum to the left of your house IF those requirements are met. He approaches you.
The door itself is to the right of the house. The street that leads to the factory and ultimately to the red light district. With the key in your inventory a door on the left wall is clickable.