Hi @sopu446,
I think some more information is required. Like what device do you have? balenaOS version? Development or production image?
And what are you trying to obtain? Almost everything can be done using SSH or Docker API functionality. I suggest reading the Balena docs to know how BalenOS works 
I have Raspberry Pi 3B+ and after typing something it asks me to login but i don’t get it which username or password should i use to login there
was trying network-wide ad-blocking with Pi-hole and am not able to install balena CLI tools
@sopu446 is it a “Development” version device? Only those will have prompts on that screen. If it’s a Development version, the username is root, with no password. See the differences between the development and production images in the documentation.
This will connect into the host OS, not into your application, just FYI.
You also mention that you cannot install balena-cli. What sort of issues are you running into?
not able to implement the command using the npm code, it says npm command not found.
@sopu446 have you installed Node.js? Looks like that might be missing, and that is a listed requirement for the CLI https://github.com/balena-io/balena-cli#requisites
then how can i install Node.js? please am a newbie to all these.
https://nodejs.org/en/download/ should get you going if you haven’t already.
That will install node and npm.
From there you’ll need to follow the Windows-specific details at https://github.com/balena-io/balena-cli/blob/master/INSTALL.md#npm-installation
If you are on windows, I would recommend using the standalone version of the cli, so you don’t have to install node.js
You can find a video explaining the installation process here: https://www.youtube.com/watch?v=j3JoA1EINUA
Thanks