[tumblr] tutorial
see that little grey heart outline down in the corner on each post?
that's a SOUL receptacle! click it to give that post a SOUL.
if you've already given that post a SOUL, you can click it to destroy it. this is irreversible, but you can give the post a different SOUL by clicking the now-empty receptacle.
you get 1,000 SOULs a day to do with as you please.