How can I get him to be quiet when it's time to go to bed?
I have a 6 week old puppy, and I'm training him to potty outside.
I've read that if you keep him in a kennel they can learn to control their bladder, but when it's time to go to sleep he starts crying, I don't want to give up but there's people that have to work.
Is there any other way for me to train him without making him cry?
What you're doing is absolutely correct, and crate training is most definitely the fastest and easiest way to housebreak a puppy.
There are a couple of things you need to realize though.... firstly that at 6 weeks old he is basically a tiny baby (puppies actually shouldn't leave their momma and littermates until they're at least 8 weeks old) and he has pretty much no control over his bladder or bowels yet. That doesn't even really begin until he's about 8 weeks old.
Secondly, it's natural for him to cry when separated from you, it's natures way of keeping him safe if he were in the wild - because a puppy all alone is likely to die.
Only in rare instances does a young puppy accept being crated without crying and complaining, and the only thing to do is to ignore the noise as long as you know that he doesn't need a potty break. It could take a week, or longer, for him to realize that his complaints fall on deaf ears unless he actually NEEDS to go, but he will learn if you're patient and give him time.
BUT up until he's somewhere between 12 and 16 weeks old he'll probably need one (at 6 weeks maybe as many as three or four) potty breaks during the night. If he's been sleeping, or quiet in his crate, for a while and then begins to cry... take him outside right away so that he begins to learn what he's supposed to do.
Housebreaking can be challenging but if you approach it the right way and are patient, the puppy eventually learns what's expected of him. I strongly suggest that you read both these pages on my site as they have lots of tips and advice to help you...
Puppy Crate Training
Housebreaking A Puppy
Best of luck with your new puppy.