Let understand the problem..
You said you downloaded the Raspbian and NOOBS from the official site" for me that's bit confusing..
You just need to download NOOBS, unzip the files in a folder and copy all the content in the formatted SD card. Then power on the Pi- (but before you power on, make sure you insert the SD card properly and are having a keyboard mouse and Monitor connected to the Pi and then power on the pi).
Note: NOOBS - stands for New out of the box software
Because you have the NOOBS software (unzipped) in the SD card, so when you power on the Pi, after initial configuration the first screen you should get is the list of OS that are available in NOOBS for installation (see below).
So now from the list of OS available you need to select Raspbian ( or any other OS, based on your need to start the OS installation) - you need your keyboard or mouse you select the appropriate OS and that you can see on the screen if you are connected to Monitor.
Note: you don't need to download Raspbian separately..
Hope this help
(i would recommend the keyboard and the mouse to be connected.. to the powered USB hub)