How to introduce a new toy to my dogs?

I have three chihuahua's, I love them sm and I ocasionally buy them things, usually food bowls, leashes, collars and that sort of things. I've been trying for a time to buy them toys because I've seen the younger one (around 4 years old) to be playing with random objects. So i decided to buy them, especially him, a toy; but they just ignore and it ends rotting on a random corner. Is there something I am missing? Like something I can do to teach them that it is for them, I thought that as the younger one just grabs any object to toss it around, he will just pick the toys I bring and play with them, but he keeps on playing with an old bottle that he found.