ADB stands for android debugging bridge which connects the android and your pc via usb cable.
but it is still just not connection but much more than that.
Its usage are very wide and powerful also.
You should have:
USB Debugging on;
USB Data cable;
*Download Adb driver
*Extract and Install the downloaded file.
*Now you need adb Executable.
Download it from here.
Extract and open folder.
*Navigate till you see adb.exe
*Now press Shift+right click and click open command prompt here.(You can use cd command too to navigate upto this folder.)
*Connect your android throgh usb cable.
adb devices //will list android(s) connected
adb shell mkdir /sdcard/folder001
//used to make directory
You are done!!!