I cant create .asc or read the installation documentation

[SirRufusss]

Hello Heads-Team,

Unfortunately I can't find out from the installation documentation how to create this .asc file.
I try to write to you what I have done and hope that you will explain the next step to me

1: I downloaded a Debian.iso and verified it for authenticity with SHA256.
2: I then moved this .iso to a USB stick
3: I insert the USB stick and enter the following in the command line:
“gpg --output Debian_iso.sig --detach-sig debian.iso”

Unfortunately I get the following back:
“gpg: error running ' bin/dirmngr' property not installed”

Please tell what i can do and how i create this annoying signature-data