Cannot Convert From String To Boolean And Int To String

I have errors in the "if" and both "else if" ... The compiler says "cannot convert from String to boolean and int to String ...

instructions:

1. Add two private instance variables, String courseName and char grade to this class.

2. Add accessor and mutator methods for these instance variables.

3. Add a method register which receives an integer data type and returns String data type according to the argument passed to it ("Math" for 1, "English" for 2, "No course" for any other input)

What I have so far:

package assignment9;
 public class BannerUser
{
private int userId;
public int getUserId()
{
return this.userId;
}
public void setUserId(int userId)

[Code] ......