Raspberry Pi 4 Raspbian OS first look. Running with 2.4A power adaptor
You should use a 3A charger the official one is a good price for a usb charger with cable.
It looks like you may only need a 3A power supply if you plan on plugging in devices that require power from the Pi.
"At 3.4W idle — a figure which may come down with post-launch firmware optimisations— and 7.6W under load" ***from the webpage linked below***
https://medium.com/@ghalfacree/benchmarking-the-raspberry-pi-4-73e5afbcd54b
Model Raspberry Pi 4 4gb first look
Also coming soon speed test compared to model b+ from 2014
Emulators and mine craft Pi test
The 6 way mains adaptor In this video with 2 x 2.4A usb sockets and switches
https://amzn.to/2O8AniK
Link to Raspbian OS and how to install
https://www.raspberrypi.org/downloads/raspbian/
More Pi content here
https://www.youtube.com/playlist?list=PLMJAjiTgBtFnaITgDfjTnsL9RlnyPTl7M