When you're posting a new message, there's 6 tabs above the text box area.
By default, you're in the "Compose" tab.
To attach a picture, click on the "Options" tab.
Just below the tab name, it says "File Attachment" and "Add/Update".
Click on "Add/Update".
A new window opens and then specify whether you're going to upload or link from a URL. If uploading, click "Browse" and follow the path on your computer to the picture. In that window, click on your picture then click "Open"
It'll then go back to the window where you specified whether to upload or link from a URL. On that window, click "Save"
Your picture is now attached to the post.
By default, you're in the "Compose" tab.
To attach a picture, click on the "Options" tab.
Just below the tab name, it says "File Attachment" and "Add/Update".
Click on "Add/Update".
A new window opens and then specify whether you're going to upload or link from a URL. If uploading, click "Browse" and follow the path on your computer to the picture. In that window, click on your picture then click "Open"
It'll then go back to the window where you specified whether to upload or link from a URL. On that window, click "Save"
Your picture is now attached to the post.