The URL format for submitting a thing is the following:
Replace USERNAME with your username on Flattr
Replace URL with the URL of the thing.
Replace TITLE with the title you want to for your thing.
Replace DESCRIPTION with the description for your thing.
Replace LANGUAGE with the language of your page, a list of the alternatives can be found here.
Replace TAGS with the tags you want your post to be tagged with. Multiple tags are separated with ,
Replace HIDDEN with = 1 if you want to hide the things from public listings on flattr.com.
Replace CATEGORY with one category from the list of categories found here.
The URL you get from this can be linked in anyway you want, with text or image link.
If you want an image as a link you can use this icon found here: https://flattr.com/_img/icons/flattr_logo_16.png or this button found here: https://api.flattr.com/button/flattr-badge-large.png
Note: The thing will submitted to our catalog when it’s flattred for the first time.