This link has even more extensive ways to do it
The way that I've seen most people do it (have a look on the Raspberry Pi forums), and have done myself with success is using /etc/rc.local.
All you need to do here is put ./myscript in the rc.local text file. If it's in python, put python myscript.py.
This literally is "a simple solution, (like dropping my script in some "startup" directory or something similar)"- maybe search on the forums when you're having questions as well, this solution came up on the first 4 results of a google search!
i need to run a QT application on BOOT. and i want to disable all controls like minimize application, close application.
Anyone have experience in this? please help me.
Sharing a tip that can be very useful when working with Raspberry pi GPIO, The GPIO Pinout is designed to be both a quick and interactive reference to the Raspberry Pi GPIO pins, plus a comprehensive guide to your Raspberry Pi's GPIO interfaces. It also includes dozens of pinouts for Raspberry Pi add-on boards, HATs and pHATs.
This Pinout.xyz gather useful information about the Raspberry Pi GPIO interface and add-on boards and invite board manufacturers to produce their own "overlay" files which describe which pins their Pi add-ons use. It's very handy when comes quick prototyping.
more details: https://pinout.xyz/