You can invite other members to a Slack channel by following these steps:
Click "View all members of this channel" at the top right of the chat window.
Click "Add people".
Select "Add to [channel name]" and click "Continue".
Search for the member you want to invite, select them, and click "Add".
If the person you want to invite is not yet a member of your Slack workspace, they must first join the workspace before they can be added to the channel.
For more detailed instructions, please refer to the Slack Channel Usage Guide.