To get started you need a Raspberry Pi (you should buy the new Pi 3), 8 GB SD card (minimum size), a monitor, HDMI cable, mouse & keyboard and image of an operating system available at raspberry pi website. First get the OS to boot up, get used to the OS. Like if you are using Raspbian then you should know basic commands to be used in terminal. All the commands are available online. Then after you know all basic commands you can start building programs on Python and use GPIO pins on RPi. Most of the tutorials are available on YouTube, but if you come across any problem that you are not able to find on internet, you can always post your problem here at collaborizm.
Best of luck!