Cannot generate Apple Certificate Signing Request

I have built a Phonegap app and am trying to run it on an IPhone 4. One of the many many things required by Apple is a Certificate Signing Request. The instructions for doing so on their website are as follows: "In the Applications folder on your Mac, open the Utilities folder and launch Keychain Access. Within the Keychain Access drop down menu, select Keychain Access > Certificate Assistant > Request a Certificate from a Certificate Authority." I am completely new to Mac's and am working off a friends computer. Its running OSX 10.8.3. When I launch Keychain Access, there is no Keychain Access drop down with Certificate Assistant. This is what I see: Where do I find Certificate Assistant > Request a Certificate from a Certificate Authority?