While in the game, press the "p" key.
Go into your TEF screenshots folder (usually C:\Program Files\Tale of Tales\The Endless Forest 3\screenshots )
Edit the screenshot if you want.
Upload to a host site such as www.tinypic.com or www.ripway.com or www.photobucket.com
Post the new URL of your image to create a hyperlink to it, or use an image tag to display the image directly on the blog.

It is created when you install the game, so it should already be on your computer.
I run XP, though. The location might be slightly different for Windows 7 users.
You should also have a folder in your start menu from the installation, and it should have a shortcut to your screenshot folder in there.

So, i'll try that then

You press P to take the screenshot. It doesn't open the folder; you have to do that yourself.

Hmm.. maybe when you click on the start button, enter "screenshots" into your search bar.

I'm afraid I don't know enough about Windows 7 to tell you exactly where it is, and I've got to get going for the night (have to be up early tomorrow). Hopefully someone who knows a little more about the OS can give you a hand. Good luck!

Click on these things in order: Start>Computer> Your C drive> Program files> Tale of Tales> The Endless Forest 3> Screenshots

Then click on the "compatibility files" button. Your screenshots should be there

Don't forget to move them to an easier-find location such as your pictures folder so you can find them. You will have to manually do this each time you want to post a screenshot.

Edit: Also remember that you have to upload a picture to an image site like photobucket or tinypic and get the link from there to post it.