First I would suggest trying to post a picture without re-sizing, sometimes it works, we are looking into this again.
If you have to re-size then the first post on this thread has the links on how to do this, on my computer this is how I get the pictures onto a post but it might be different with your Samsung galaxy note 3
When you write the post, scroll down the page and there is a "browse" button, hit that and then from your folders choose which picture you wish to upload.
When you have found the picture double click on it and then hit the "submit" button.