转正是要向外贴找人广告的, 因为要公平竞争,不可黑箱作业.

If the company wants to convert you, then HR need publish this AD position in company web site.
However, internally, they all knew this position is open for you ONLY.
You can apply the position after you see the job AD.
In normal case, your manager will let you know ans ask you to apply this position from company web site.
Enjoy holiday!