I have a 13 month Rott of very high pedigree but is coward.
He get scared while passing a manhole drain, loud noises startled sometimes. A very soft dog he thinks every body is his friend and for that reason I don't have any stranger pet him.
I scared that he might bite someone in fear as he grows to be an adult.
What can I do to build his confidence?
Oh Michael, your Rottie is just a pup and his behavior is fairly normal. Rottweilers are just like any other dog, and it's natural for them to be nervous about unusual stuff , loud noises and so on. The more exposure they get to these types of things (socialization) the easier it is because they get used to them.
We are all anxious about the unknown, or things we don't understand. From your dog's point of view a manhole cover is an odd thing, and he doesn't know what those loud noises mean!
Some dogs are naturally less confident than others, but this doesn't make them cowards. With love and empathy you can help him overcome his fears or anxieties, but if you try to force him to do stuff that scares him, or to 'toughen him up' you will make him more nervous.
Also, it's natural for a well-bred dog with a sound temperament to think people are his friends - that's what he SHOULD think! This doesn't mean he wouldn't protect you from danger, or from someone with a dangerous intent. He's intelligent enough to know the difference.
A friendly dog is unlikely to bite someone out of fear, but a dog who isn't allowed to be social with strangers, or to have lots of interaction with people (especially one who is anxious in other areas) just might end up being a fear-biter. But it wouldn't be happening naturally, more as a result of his lack of socialization and not enough confidence building and interaction with people.
I strongly recommend you read the pages on my site that talk about the Rottweiler temperament, so that you understand your dog better. Also, getting some help from a professional trainer might be a good idea. That way your Rottie can get interaction with other people and dogs in a safe and controlled setting, and you'll get the info. you need to help him with any insecurities he has.
I wish you both the very best of luck and hope that you can come to see the strengths in your Rottweiler, rather than the weaknesses. He's just a dog who needs to be loved, trained, socialized and accepted for who he is.