Need help with a simple DC motor project

Hello all.
I'm making simple project that is based only on a 12V 300ma DC motor.

I know it's without Arduino but I got to this hobby through Arduino and the help of the wonderful guys of this forum, so once I'm again I need help.

So I just need to understand I got the wiring goes because It goes to the 220V in my house and that could kill me.

My plan is to connect a 12V 1A DC adapter, then connect it toNut Round Hole DC Socket, that to toggle switch, and then to the motor.
Please let me know if I got it correctly.
Another question, there are Nut Round Hole DC Socket and switches with 3 pins, not 2. Why is that? the tutorial for this project ( here ) uses 3 pins and I couldn't get why. THANKS

Adding a sketch of my plan

For a socket, the third pin is connected to the + pin when nothing is plugged into the socket. This is often used to connect an internal battery in place of the external power when the external power is removed.

For a switch, a Single-Pole, Double Throw (SPDT) switch has one Common terminal, a Normally Closed (NC) terminal that is connected when the switch is 'off' and a Normally Open (NO) terminal that is connected to Common when the switch is 'on'.

Ok I think I got it. So in my case I need a nut with only 2 pins?
And regarding the toggle switch, Can't I just use a 2 pin switch and only connect the + side?
In a 3 pin switch, I understand where the +/- are connected but where the third pin, when it's off. Thank you John

Edit: I added to the original post a sketch, could you have a look at it please?

The sketch looks good. You can just leave the unused terminals of the socket and switch unconnected.

I have ones with 2 pins, so I'll just use them.
Thank you