I would most definitely recommend that you start out with the SOAP::Lite
package as this provides a much higher-level interface for those unfamiliar with SOAP design and implementation. Additionally, it is this package which is most widely documented and most commonly referenced in connection with SOAP implementation in Perl.
Additionally, it may be worth taking a look at the the SOAP::Lite user guide and SOAP::Lite cookbook for example usage and code.
perl -le "print unpack'N', pack'B32', '00000000000000000000001010101000'"