Gmail will automatically detect spam (junk mail) and send it to your Junk Mail folder. There is no need to report these attempts to the IT Support Center. To increase Google's ability to detect these messages, please follow the processes below.
You can increase Gmail's accuracy of automatically detecting the spam by marking any spam Emails that come through your inbox as spam instead of just deleting it. You can learn how to mark your spam by visiting Google's Remove Spam help page.
If you find an email inaccurately marked as spam, you can unmark them as spam and place them back into your inbox. You can learn how to fix this on Google's Legitimate mail is marked as spam help page.
Recognizing Phishing Attempts will explain how to spot phishing attempts.
To learn more about phishing and to report something in your Gmail inbox as a phishing attempt: https://support.google.com/accounts/answer/75061?hl=en
For those phishing attempts which seem especially convincing, please report them to US-Cert: http://www.us-cert.gov/report-phishing