Undo the nut and rock the arm.

You have a 6th gen, btw. This is the 5th gen side of the forum. Doesn't matter in this case since it's the same answer for both.

 

You have a 6th gen, btw. This is the 5th gen side of the forum.

Thread moved to 6th generation forum

 

am i supposed to undo another nut because the arm is stuck there

 

Push on the arm a bit up and down. That should pop it free. If not, they make wiper arm pullers. Fairly sure AutoZone loans them out.

 

When putting the new arm on there are black alignment lines on the windshield that line up with the blades when 'parked'.