Creating Transact Procedures

i need to create procedures with if statements
i am confused since i did not learn much about it

i need to do the following
a)If the employee is not a manager the procedure should print “Name is Individual Contributor”
b)If the employee is a manager, the procedure should list all the employees that report to that manager.
c)If the supplied EmployeeID does not exist, the procedure should print “Employee with ID NNN does not exist.”

This is the table
CREATE TABLE Employee
(EmployeeID int NOT NULL
CONSTRAINT Employee_EmployeeID_PK PRIMARY KEY
, Name varchar(50) NOT NULL
, SIN char(9) NOT NULL
, LoginID varchar(256) NOT NULL
, ManagerID int NULL
, BirthDate smalldatetime NOT NULL
, MaritalStatus char(1) NOT NULL
, Gender char(1) NOT NULL
, HireDate datetime NOT NULL
, VacationHours smallint NOT NULL
CONSTRAINT Employee_VacationHours_DF DEFAULT ((0))
, SickLeaveHours smallint NOT NULL
CONSTRAINT Employee_SickLeaveHours_DF DEFAULT ((0))
, IsManager bit
, NumReports int
, ModifiedDate datetime NOT NULL
CONSTRAINT Employee_ModifiedDate_DF DEFAULT (getdate())

I am thinking of using IsManager as TRUE or FALSE
but i dont know how to put it together

this is my sad try for now
CREATE PROCEDURE ListOrganizationMC
@employeeID int,
@managerID int,
@isManager bit
AS
select name
from employeemc

if @ismanager = 0
Begin
Print 'Name is Individual Contributor'
end
SET @employeeID = @managerID;
go

im sure the top part of the parameters are wrong
i just want to enter one parameter