You really need a diagram to visualize what needs to be done. Remove the entire tensioner assembly. Push the plunger all the way through, then feed it in again, but just far enough to get it back together. Once oil pressure is applied it will ratchet into place.

If you try to put the tensioner back in without pushing the plunger out and restarting it, you can easily break something. I strongly recommend getting a manual.

Good luck,