begin
fnd_global.apps_initialize(&user_id,&responsibility_id,&org_id);
mo_global.init('PO');
end;

To get org id, user id and responsibility id:
select user_id from fnd_user where user_name = ;
select responsibility_id from fnd_responsibility_tl where responsibility_name = ;
select organization_id from mtl_parameters where organization_code = ;