crates come in various sizes...get one that will hold him as an adult...& as far as introducing him to one now...start gradually...sure he won't be happy about it initially but that said...make it a pleasant , safe place..NOT one of punishment.

begin as i mentioned by leaving the door open when he is allowed free range. place toys inside it. feed him inside it & shut the door when he eats. this will serve to re-enforce that it is his spot. you can have him sleep in it at night.

having him upset some is a small price to pay compared to having your belongings destroyed.

you can purchase the crates at most pet stores...or even check free cycle...just make sure you get one large enough for him. some dogs like it covered (a wire one) in which case just toss a sheet or a blanket over the mesh. get a nice crate pad for it as well.

when he is left inside the crate remove his collar. you don't ant him getting caught up on the crate with it & getting tangled.

a suggestion...enroll in a dog obedience class...they will help with some of the basic questions or if nothing else get some books out of the library.
only give him appropriate toys...don't offer him shows, etc to play with...you can get marrow or soup bones from the store...uncooked..these are great for him to keep busy with...no cooked steak bones, or chicken bones.

stumpy