Summarize:

In most regions, the only time you can hack a WPA or WPA2 network is when the network either belongs to you or belongs to someone who has given you explicit consent to hack the network. Hacking networks that don't meet the above criteria is illegal, and may constitute a federal crime. Kali Linux is the preferred tool for hacking WPA and WPA2. You can download the Kali Linux installation image (ISO) by doing the following:  Go to https://www.kali.org/downloads/ in your computer's web browser. Click HTTP next to the version of Kali you want to use. Wait for the file to finish downloading. You'll need to use a flash drive with at least 4 gigabytes of space for this process. . This is necessary in order to be able to use the USB flash drive as an installation location. You can also use a Mac for this step. Open the flash drive, then drag the downloaded Kali Linux ISO file into the flash drive's window. Make sure you leave your USB flash drive plugged in after you finish this process. To install Kali Linux on your computer, do the following:  Prompt your Windows computer to restart.  Enter the BIOS menu. Set your computer to start from your USB drive by finding the "Boot Options" (or similar) section, selecting your USB drive's name, and moving it to the top of the list. Save and exit, then wait for the Kali Linux installation window to appear (you may have to restart your computer one more time). Follow the Kali Linux installation prompts. You can find Wi-Fi cards online or in tech department stores. Make sure that your Wi-Fi card allows monitoring (RFMON), or you won't be able to hack a network.  Many computers have built-in RFMON Wi-Fi cards, so you might want to try the first four steps of the next part before buying one. If you're using Kali Linux in a virtual machine, you will need a Wi-Fi card regardless of your computer's card. Enter your root username and password when logging in. You will need to be on your root account at all times during the hacking process. Doing so will immediately prompt the card to begin setting up and downloading drivers for itself; if prompted, follow the on-screen instructions to complete the setup. Once you're done with this step, you can proceed with hacking your selected network.  If you've already set up the card on your computer before, you'll still have to set it up for Kali Linux here by plugging it in. In most cases, simply attaching the card to your computer will be enough to set it up.
Understand when you can legally hack Wi-Fi. Download the Kali Linux disk image. Attach a flash drive to your computer. Make your flash drive bootable Place the Kali Linux ISO file on the flash drive. Install Kali Linux. Buy a Wi-Fi card that supports monitoring. Log into your Kali Linux computer as root. Plug your Wi-Fi card into your Kali Linux computer.