Accidents Are Your Fault
If your Rottie pup has a little accident on your carpet, remember, it's your fault! You must watch the puppy every second during the early weeks of bringing him home. The best way for him to learn is by teaching him where to go and making sure he doesn't go where he's not suppose to. A loud "No" while catching him in the act (not after), followed by a quick trip to his area, will certainly help him learn sooner. A key to easy house training is to establish a routine that increases the chances that your Rottie pup will eliminate in the right places and to some extent the right time (when you're there).
Praising and rewarding is also important during the early phases of house training. Whether you decide to crate train or not is up to you but either way, your dog should be kept on a scheduled feeding so you can learn his cycles.
Crate Training is Natural
In a wolf den, a mother cleans the pup's feces until there old enough to defecate away from the den. The pups learn this at an early age and will inherently keep their crate or den clean. If introduced properly, a puppy will look at a crate the same way a wolf puppy will look at his den. It will be a safe and secure home for him. This is probably the easiest way to house train your pup. After meals and when he wakes simply take him outside to relieve himself. If he does not do so within 10 minutes put him back in and wait 20 minutes and try again. Reward your puppy only after he finished with praise and a treat. If you decide not to crate train, then the same basic idea would apply. Keep him in a small confined and comfortable area where he feels safe and secure.
Crate Style & Size
If you travel a lot then you probably will want to purchase a light weight portable crate. The size of the crate should be at least 48" so your adult Rottweiler can easily turn around once inside. While still a puppy, you can block off part of the crate so as to make it more cozy and comfortable. If you don't block off part, your puppy may relieve himself in it. If you purchase a puppy from a pet shop where they are forced to relieve themselves in their pens or crates it will be much more difficult to train.
Frequency
When your puppy has to go, it has to go NOW! Puppies can't begin holding their bladder until their around 12 weeks old. Your Rottweiler will often have to go once in the middle of the night (be prepared), whenever he awakes and before he goes to bed. He will normally have to go after each meal and after drinking water.
Tethering
If you don't trust yourself enough to watch your puppy then consider using a six foot leash attached to your belt. This will keep your puppy close to you so you can keep an eye on him.
Correction
Never hit a puppy for any reason and never scold him after he has an accident, it's too late and it's YOUR FAULT! You must try to prevent an accident before it occurs. It's not a matter of if your puppy will have an accident it's a matter of when. Are you watching him? You will miss an early sign at some point in his training and an accident will occur. When you catch him in the act, shout "NO" with a loud voice and then immediately take him outside to his designated spot. Reward him only if he goes, otherwise put him in his crate but do not scold him again. Your puppy will not remember 1 minute after an accident why he's being scolded. Remember, his home should NOT be a punishment so don't scold him you put him in it.