Problem with arithmetic operators for class?

[replacementaccount]

I have made a custom class matrices class which allows me to add, multiply, subtract (etc.) matrices. I have the following method for multiplication but I get an error that says
'invalid use of 'this' outside of a non-static member function'
How can I refer to the current instance without getting this error.
void operator *(Matrices& matrix2)
{
this.multiplyMatrix(matrix2);
}
Thanks in advance.

[helios]

void Matrices::operator* // etc.
Also:
1. this is a pointer, so you have to say this-> not this.
2. An overload of operator*() should not modify this.
3. Matrices is a very lousy name for a class that contains a single matrix.

[replacementaccount]

I just figured it out. Thanks anyway.