Are these used to make Dragon Armor when smithing is 100%, or should I just sell it? I want to make that Armor someday but It's pretty heavy and I don't know where a safe chest is.

Yes it is used for crafting dragon armor. It is not that important as they are a renewable and bountiful material. Lots of dragons. I would recommend placing them in a house. Such as whiterun.

Buy a house for it. You want to keep those. They're heavy, but it's worth having them for the armor later on. And also when you need some cash, they're something that you can keep just for that. Don't sell them immediately.

it doesnt really take that much to make the armor, just get around 15 of scales or bones and sell the rest

I just got 100 today and dragon scales are used for armors. But i dont know what dragon bones are for. Safe chest: your house (least expensive is in witerun)

I've been working on getting my smithing up. I have a ton of Dragon Bones and Scales.

What I do is sell them off in beginning and start saving them when I hit 90 smithing. Buying a house in Whiterun would get a safe chest and IRC the alchemist's shack is safe place to put your stuff, but don't take my word for it.