What is an entitlements plist and why do I need one?

I have been following the instructions for app store distribution in the iOS Developer Program Guide, and I did everything it said to do, but when I try to build the app, it says "the entitlements file "path of file/entitlements.plist" is missing." I tried adding a template one and it says

Command /usr/bin/codesign failed with e开发者_C百科xit code 1, and

Application failed codesign verification. The signature was invalid, or it was not signed with an Apple submission certificate. (-19011)

I don't think this has to do with the certificate because I have followed Apple's intsructions about the certificate, but it doesn't say anything about an entitlements.plist. How do I get my app to work so that I can submit it to the App Store?