First you need to a iMac or mac mini and then need xcode that is avaliable on developer.apple.com
download the xcode and install them. after installing open xcode and then new project.
For more detail go on   developer.apple.com
To create new application open xcode--> new Application choose single view application click next check with xib file and ok.
now your new peoject is created that have appDelegate classes and three other classes .h, .m , .xib
go to xib and drag and drop a button from tool bar. now press command +r and your first application is running.

Thanks