Welcome, and hope you have a good time with it. Go slow until you understand the controls.
The tiller attachment - actually, any rear implement - is connected to the tractor by the 3 point hitch. It looks like your lower two arms are attached correctly to the implement. That's two out of three. To get it off of the tires, attach the top center link and then adjust that top link to be much shorter. Shortening the top link - also called the center link - will rotate the tiller attachment away from the tires. THEN you can adjust the two lower arm chains to hole the tiller centered side to side ....and finally you are ready to raise and lower the tiller with the 3pt control.
I would recommend is that you leave the PTO shaft disconnected for awhile. Running a tiller requires more thought and I also recommend that you get someone to help set it up the first time you power up the tiller. Until then, just use it as a counterweight, spend the time driving && learning the tractor, using the loader, and learning the basics of how to adjust the tiller and 3pt hitch.
Enjoy!
rScotty