How to Enable the Buddy List

Hi all,

I have downloaded drupal5 and tried to enable the buddy list.. But, it shows some warning messages and the selection box is disabled.. The messages are given below

An advanced voting module that includes plurarity voting, instant-runoff voting, and electoral lists.
Depends on: Votingapi (missing)
Required by: Ranking (disabled), Selection (disabled

Please guide me, how to fix the above problem..

Thanks in advance.