Need some help extending Employee form

Need some help extending Employee form

I need to add list of Projects to Employee (zero or more, indicates list of projects employee is assigned to).
Would appreciate on a hint on how to approach this task?
To be more specific, this is what I tried:

- Created a custom Form "Projects"
- Added field "Project Name" to it
- Started to look how can I
1) Allow to select zero or more projects when editing Employee
2) Show list of projects when viewing Employee