To allow embedding you can do it on single Tracks or Full Albums.
Single track: Go to http://virb.com/hub/contribute/manage/audio
Edit the song you wish to allow embeds for and at the bottom of that Edit page you will see "Allow to be embedded on other websites" click that check box, then save changes.
Then if you go to your profile you can hit the button next to that song in your playlist and click "Embed This Track" and it will give you the code. You can also go to the page of the specific track to also get the Embed option.
For full albums, go to http://virb.com/hub/contribute/manage/audio
Click on the album name on the right side under Albums and edit the album you want to allow to embedding for.
Scroll down till you see the option "Make this album embeddable on other websites" click that, then Save Changes. Once the page refreshes, go back to where it says "Make this album embeddable on other websites" and click "Copy Embed Code" and you can now embed that entire album on an external website.
We will be making this process easier in the future but for now if you have any other questions feel free to contact us at http://virb.com/help/contact.