To add a signature to a post you must first create one; this is done via your profile.
To create a signature;
.Click on the profile button on the bar.
.Click on the word 'avatar' that is above the grey marble divider
.if you are uploading an image from your computer; click on the 'Choose File' button and find your image, select it and click on the 'open' button. then click the 'Save' button.
.if you are uploading or linking from a URL; paste the url location into the box, and click the 'Save' button. this URL must begin with 'http' and end with .jpg .gif or .png
Images for avatar must be 150 by 150 pixels or less and cannot exceed 64KB.