You have to create a folder in GooleEarth software : right click on "my places", then "new" and "folder".
You put all your placemarks in this folder.
Then right click in your new folder, chose "save as" and save where you want in your hard disk.
Go to the right forum, chose "start a new topic", write your text, click on "continue", then give the way to your folder ("attach your file").
That's all folk !