clan-cli/secrets: update some error message in encrypt_secret

Found that while reading through some code.

pkgs/clan-cli/clan_cli/secrets/secrets.py

@@ -27,7 +27,7 @@ from .sops import (
     read_keys,
     update_keys,
 )
-from .types import VALID_SECRET_NAME, secret_name_type
+from .types import VALID_SECRET_NAME, VALID_USER_NAME, secret_name_type
 
 log = logging.getLogger(__name__)
 
@@ -158,8 +158,32 @@ def encrypt_secret(
     admin_keys = sops.ensure_admin_public_keys(flake_dir)
 
     if not admin_keys:
-        # TODO double check the correct command to run
+        users = list_objects(
-        msg = "No keys found. Please run 'clan secrets add-key' to add a key."
+            sops_users_folder(flake_dir),
+            is_valid=lambda name: VALID_USER_NAME.match(name) is not None,
+        )
+        msg = (
+            "No admin keys found.\n\n"
+            "Please run 'clan secrets key generate' to create a key. "
+        )
+        if (count := len(users)) > 1:
+            msg += (
+                f"Then run 'clan secrets users add-key' "
+                f"to add the key to an user you already have "
+                f"({', '.join(users)}), or use 'clan secrets users add' "
+                f"to create a new user with the new key."
+            )
+        elif count == 1:
+            msg += (
+                f"Then run 'clan secrets users add-key {users[0]}' "
+                f"to add the key to the user you already have, or use "
+                f"'clan secrets users add' to create a new user "
+                f"with the new key."
+            )
+        else:
+            msg += (
+                "Then run 'clan secrets users add' to associate the key with an user."
+            )
         raise ClanError(msg)
 
     username = next(iter(admin_keys)).username