Curl::Multi post

I'm having trouble finding documentation on the curl-multi gem.

I need to post some xml to a webservice - I've done this in PHP

so far :

require 'curl-multi'
curl ="url", "xml", ?)

The question mark in the code above is what I'm having trouble with.
With nothing there I get a "wroong number of arguments - 2 for 3"

I know it's something absurdly simple that I am missing...

Nevermind - I’m going to use the Curl::Easy way instead.