Watch this video: Creating a Bibliography/Work(s) Cited
Options for creating your citations:
Bibcitation - citation creator; keep all your work in one place
In the Gale Databases (and others) the citations are already created for you- you can copy/paste these into a Works Cited or Bibliography page.
Use the already built-In "Citations" option under TOOLS in your Google Document
Add the "add-on" for Easy Bib Bibliography Creator under ADD-ONs in Google Documents
You can also consult the 204 High School Research Handbook.