Clicking on Extensions opens a window with a search engine through which you can search, select and add new command categories to the editor.
To add the AQ:bit extension to the search engine, copy and paste this link:
https://github.com/bosnivan/pxt-aqbit#
THE FIRST PROGRAM FOR AQ:BIT
Create a basic program for the AQ:bit that will read temperature, relative humidity and air pressure, and microparticle concentration every 5 seconds and display each value on the micro:bit's screen.
By creating this program you will learn:
• Add an extension for AQ:bit programming
• Read and print values measured by AQ:bit
• Use commands: on start, put PMS in passive mode, forever, show string, show number, read BME temperature, read humidity, read pressure, read PMS 2.5, clear screen, pause (ms)
Now comes the creation of the program itself. First , select the command put PMS in passive mode from the AQ:bit category and place it in the on start block. This command is used to activate the sensor for measuring the concentration of microparticles at the beginning of the program.

Given that you want this program to be executed continuously, the other commands must be placed in a forever loop. Add first the commands that will print the temperature value. From the Basic category, select the show string command, place it in a forever loop and type ˝T:˝ into it as a sign that the value that will be printed after that text refers to temperature.
The temperature value is a number, so add the show number command from the Basic category, and set the read BME temperature command from the AQ:bit category in place of zero as its argument

Repeat the procedures from the previous step, in which you programmed the temperature measurement, to measure the relative humidity ( show string ˝H:˝ is how number read humidity ), pressure ( show string ˝P: ˝ and show number read pressure ) and the concentration of microparticles of size 2.5 micrometers ( show string ˝PM:˝ and show number read PMS 2.5 ). At the end, add the clear screen and pause (ms) commands from the Basic category in order to set the micro:bit screen to be cleared after reading the printout and to prepare for the printout of new values that will be measured after 5 seconds. The program will look like the picture.

Switch the program to micro:bit and check the values read by your AQ:bit. The temperature value is printed in degrees Celsius, the relative humidity in percentages, the air pressure in hectopascals, and the concentration of microparticles in the number of particles per million (ppm).