If you are on your iOS device, I think it defaults to try to get you to use your mail app, I think. If you are on a computer, just go to iCloud.com, and click the cloud symbol, (for some reason it defaults to find my ****
In case you're unaware, MobileMe is phasing out and iCloud is its replacement (iCloud is not just for finding your devices, it's where the other components of MobileMe are housed, including email). You may want to migrate your MobileMe content to iCloud (using your existing email address, which will not disappear).