help. I can't find help on LaPlace transform

Where is the help for laplace transforms?
I tried

(%i9) LaPlace(sin,x,4);
                                    SIN
(%o9)                          ---
                                     4

And this is not what I was expecting!




Also I tried:

integrate(sin(5*x)*exp(-s*x),x,0,inf);

Ans it asked me if s was

(%i25) integrate(sin(5*x)*exp(-s*x),x,0,inf);
Is  s  positive, negative, or zero?

I am using winXP and when I try to respond to the question Maxima 
doesn't seem to get the response.
It just keeps waiting for my answer.
I tried:

(%i25) integrate(sin(5*x)*exp(-s*x),x,0,inf);
Is  s  positive, negative, or zero? positive;


I tried
(%i25) integrate(sin(5*x)*exp(-s*x),x,0,inf);
Is  s  positive, negative, or zero?
positive;

But no results.
What am I doing wrong?
Doug Stewart