This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Firstly you don't seem to have a primary key on the UserManager table, not really a problem but you may want to add in a surrogate primary key.
Secondly I'm not sure what your question is, have you made any ORM mappings? Your user model looks ok, but remember that each User will have 2 lists, 1 will be the list of managers (users) that a user has and the other will be a list of employees (users) that the user manages each of these will map to a different column in the UserManager table.