You can place a Snippet by using the snippet tag directly into your content.

You tell the {snippet} tag which snippet to place simply by using the Alias, Title or ID of the snippet:

{snippet alias="my-snippet"}
{snippet title="My Snippet"}
{snippet id="4"}

So to place a snippet you have given the alias copyright, you can simply place:

{snippet alias="copyright"}

When you edit the article (or module, or wherever you put the snippet tag), you will still see the tag. But on the frontend view, you will see the content of the snippet instead.

If at any time you want to change the content of the Snippet, simply change it in the Snippet itself that you created earlier, and the output will change automatically in every place where you have used the tag.