Cant find files in ubuntu system to verify

i cant verify satoshi labs signing key. Do I need to create a special file, or call it something special?

[email protected]:~$ chmod u+x Trezor-Suite-22.2.3-linux-x86_64.AppImage
chmod: cannot access ‘Trezor-Suite-22.2.3-linux-x86_64.AppImage’: No such file or directory
[email protected]:~$ chmod u+x /home/user/Downloads/Trezor-Suite-22.2.3-Linux-x86_64.AppImage
chmod: cannot access ‘/home/user/Downloads/Trezor-Suite-22.2.3-Linux-x86_64.AppImage’: No such file or directory
[email protected]:~$

Apologies in advance for my ignorance