OpenSAML user discussion

Hi,
Can any one explain me how the SAML request/response work?
The API gives a method send which will return the SAML responce. But how do 
we 
give the target end point and the remote method of the web service which will 
build the SAML responce back? Also if i am correct up to this point do we 
have a send with the same method signature in the web service to handle the 
request?
Can we get any sample code which demonstrate the request/response protocol?

Thanks in advance
Deepak