If you do not have a table to secure the dog, you can see an alternative in this video. This is a 2.5-year-old dog that has never been taught hold on a tie out to a post.
The important part is to make sure that once you secure the dog, he does not try to back out of the collar of it will create panic.

Lure the dog through the unbuckled collar held loosely in your hand, mark and drop the collar – 01:50 sec. The reason we are dropping the collar is to prevent the dog from backing up.

Lure the dog through the unbuckled collar, LEAN THE DOG AGAINST THE POLE, mark and drop the collar – 02:15 sec. You can also use the leash that is attached to the dog to prevent him from backing up – 03:00 sec.

Once the dog is comfortable, you can actually buckle the collar.Then you can start practicing basic eye contact.
After that move on to the chin rest.
The next step will be to begin the actual hold of the plastic rod