Im also embossing designs onto my pockefolds and the inserts of my invites I absolutely love it since my theme is all sand dollars and starfish. I bought most of my materials from Michaels so I could use half of coupons to save Anyways, I bought the special embossing ink. Used specifically for embossing and they have a range of different colors. Then I chose clear embossing powder they sell to put over the ink. My ink is brown so it comes out brown once I run the heat gun over it. BE SURE to angle the embossing gun so you can get even heat to the entire image. Don't hold to gun too close or else you will heat certain areas to quickly.
Hope this helps!