Developer's Guide

In the transplantation form, find "My module" in the modules drop-down
menu, then choose "Left column blocks" in the "Hook into" drop-down
menu.
It is useless to try to attach a module to a hook for which it has no
implemented method.
Save. The "Positions" page should reload, with the following message:
"Module transplanted successfully to hook". Congratulations! Scroll down,
and you should indeed see your module among the other modules from
the "Left column blocks" list. Move it to the top of the list.