Hi skytesting2019 In your post, it doesn't look like there's anything separating your commands. You need to run each command separately, one after the other, or separate them with double ampersands like this: <code>sudo add-apt-repository ppa:mozillateam/ppa && sudo apt-get update && sudo apt install firefox-esr </code> You should be able to copy and paste the above code into a terminal, press enter, type your password (note your password will be hidden and it won't look like you're typing anything, but it it is working) and press enter again. Your system will add the mozillateam ppa, get an updated list of pacakages and then install firefox-esr. You may be prompted to press 'y' or Enter occasionally to confirm you want to continue. Let us know if this helps. If this doesn't work, it would be really helpful if you could describe the error in greater detail, and copy and paste any error messages you see. Thanks!