So the first thing you need to do is to get the very basic stuff in place, which are the purchases:
- Raspberry Pi 3
- Powersupply for Raspberry Pi 3
- SD Card (Suggest min 16Gb)
You also need to ensure you can connect it to a screen (HDMI), keyboard(USB) and mouse (USB).
When all of that is in place, you need to load the installation files and do the first setup. Its rather simple, as all you need to do is to format the SD card and copy the installation files to it, insert the SD card in the RPi and boot.
The Raspberry Pi website has a very good guide how to do this using NOOBS:
Or follow the NOOBS guide here:
So once you have your RPi up and running, you can setup the remote control configuration if you dont want to keep it connected to its own keyboard and mouse. This is explained here