Play sounds/Using WMP Control in C#

[session]

First off, I wanna make only 1, 2, 3 avaliable when a variable intNumber greater or equal to 3, when intNumber is = or < 2, only 1 and 2 is avaliable to be entered in this textBox. I'm just wondering how do I code for intNumber>=3 in C#?

if(intNumber _____ 3)
{
     <code>
}
else if(intNumber _____ 2)
{
     <code>
}
else
{
     <code>
}

what should I put int the blanks? just put <= or >= ???

2nd-ly, what should I use in C# to replace Len function in VB .NET?

3rd,
i found these somewhere but there's no definition and explanations for those, can anyone explain for me?

Assignment: = *= /= %= += -= <<= >>= &= ^= |=
Logical AND &
Logical XOR ^
Logical OR |
Conditional AND &&
Conditional OR ||
Multiplicative * / %
Additive + -
Shift << >>
Relational and type testing < > <= >= is as
And what is the symbol/expression for not equal??? :s

Finally,
How do i use Exit Sub in C#?? break?
Thanks for help!