Can i combine a few amino acids in a bottle and call it a peptide? How exactly does that work?

I read that a peptide is a chain of amino acids & that proteins are a longer chain of amino acids. And that peptides act as the building blocks of some proteins. But what exactly makes it a "chain" of amino acids? How does it act as a building block to proteins such as collagen?

More so, can i and how do i go about making one?

ps. sorry if this is confusing, as i'm really confused with the topic myself.