Register for an account at zotero.org.
Download Zotero and then install the program. It's fine to accept the default settings.
Connect Zotero to your personal account. Navigate to Edit > Preferences > Sync and then log in using your credentials.
Set preferred citation style. Navigate to Edit > Prefernces > Cite and select your citation style. You may need to download an additional style.
Download Zotero Connector and add to your browser.