Welcome to Sysnative.
Don't do that. On any forum (not just here), the only time you should edit a post is (1) to correct a minor typo or (2) if no one has replied and only a short period of time has passed since the post was first submitted.
The reason why is that those participating in, or others just following the thread do not get notified of any edits. This is why many sites don't even let users edit their posts after X number of minutes has passed, even when there have been no replies.
So if you want to say more, simply post a reply with the new or updated content.