Ubuntu Server console: How to close etc/Passwd

Hi. I realize it's embarassingly silly question probably, but I'm new to Linux and I'm trying to find my way around things here.. I'm using Ubuntu Server ran in Proxmox LXC. Sometimes when I open a file e.g. etc/Passwd from console, I can't close it so the cursor would appear and I would be able to put my command in.. Last line that I can see is /etc/Passwd (END) but I have no clue how to close the file and get my cursor back.