I lost my I phone 4 s and I need the iMei number to trace. PLEASE HELP ME!

You need to have possession of your iPhone to find the iMei number (serial number), see this link:

Find the serial number and other information for your iPhone, iPad, and iPod touch - Apple Support

If you have already set up Find My iPhone on your device, try to locate it this way:

http://help.apple.com/icloud/#/mm6b1aa045

I understood, but this is a public forum. You are not talking to Apple here - never post your address here -everybody worldwide can read it. The IMEI (the serial number) is printed on the back of the lost iPhone or available in the settings. You should have written it down before the device has been lost. It may also be written on the receipt you received, when you purchased your iPhone. Do you still have the receipt for your purchase?

Have you registered the iPhone with Apple? Then you can find the serial number by signing into My Support Profile https://supportprofile.apple.com

If you've used computer iTunes to backup your iPhone.

Go to computer iTunes > Preferences...(Windows user: Edit > Preferences...) > Devices > hover your mouse over the iPhone backup, a popup will show your IMEI & serial number.

Note, you cannot use Find My iPhone using IMEI or serial number.