To be honest, you shouldn't need the manual for this. The constructor for an object should always be called using the arrow notation. Calling something with colons means that you're calling it as a plain subroutine; calling it with an arrow means you're calling it as a method.
yup, i guess i should also read the manual about OO-Perl... well, you gotta start somewhere! then again, the error message didn't really make it clear to me what the problem might have been