Zotero comes with all the most common citation styles, but many more are available to download.
To install a style:
- Open Zotero
- Go to the Zotero Style Repository page
- Search for the name of the style you need
- Click the name
- It should ask if you want to add the style to Zotero; click yes
- If it doesn't, just download the style, open the .csl file, and when Zotero asks click "install"
The new style will appear in Zotero's style lists.