Crate Training An Adult Rottie
I got a 12 year old rottweiler from a breeder and she has never been in a crate.
What should I put in the crate with her?
Can I keep her in it over night?
If this girl has never been crated a lot will depend on her personality.
Some dogs will go right into a crate and accept it without problem, but others will get stressed and anxious. Until you know how she's going to react and learn more about her personality I'd recommend introducing the crate slowly and giving her a chance to get used to it.
At 12 years old it's going to take her longer than normal to adjust to a new home, family, routine etc. and you don't want to give her more anxiety than necessary.
She shouldn't have any trouble with housebreaking as her bladder/bowel control will be good, plus she's well past the chewing-everything stage, so leaving her un-crated at night shouldn't be a problem.
I wouldn't recommend crating her overnight to begin with because that's a long time, start with short periods while you're home to see how she handles it. Although aimed at puppy owners, my Puppy Crate Training page will still have lots of tips and advice to help you. The principles are the same regardless of the dogs' age.
Put a couple of sturdy chew toys to keep her busy. Puppies are more likely to pee in their crates if there's anything soft in there, such as a blanket or soft toy. This is much less likely to be a problem with an adult, but until you see how well she does with it I'd hold off putting anything soft in there just to be safe.
Hope this helps. Best of luck.