The snippet manager can be found in Admin>Snippets. You will need access to the Admin app to use it.
Click the blue + button to create a new snippet.
Give your snippet a name (it can't be the same as any other snippet) and choose which practitioners can use it.
If you select "Automatically assign to new practitioners", any new practitioners added to your account (or newly activated) will automatically have access to the snippet.
Click "Save"
Your text snippet will now appear in the "Insert text snippets" drop down when composing a practitioner note.
You can also create a text snippet in practitioner notes.
Read about using text snippets in the same article.