You usually (almost always) need to install Debian from a non-free ISO to have this sorted out by the installation program. You can download them from the Debian page here.I can connect the internet with ethernet but i want to connect with wifi.
I fixed the problem like this.what is the output of lspci or lsusb
what is the output of nmcli dev wifi list
You may not want to post your SSIDs if they show up here. But the main thing is, do you see any wifi networks?