How can I EDIT?
After edit disappears from comment-how can u edit or cancel post?
You can't. You can flag the post and ask the mods to edit it, but I think that rarely happens. Best bet is to simply "answer" your own post with the updated information.
You can use the "Flag" option under the post and ask us to remove it so you can repost, or let us know what you would like to edit in. We're happy to do either, but bear in mind that there's no way for anyone who read your post once to know that new information has been edited in, so if there's a crucial change to make, it's better to have us remove it and repost, or, if there are already responses, to follow up with a new post.