What do you mean? You pass it around?
i'm in a coven of about 7 people. we have cake and ale [or wine and a cookie whatever available] each person takes a piece of the cake and a sip of ale but leaves some of both so after the ceremony i go outside and place it in my garden. i'm guessing you're solitary, so you do the same thing, take a bit, then leave it on your altar in from of your candles or statues representing the Lord and Lady. at the end of the circle, take them outside and place them somewhere in nature. [could be under a tree, in a pond, a garden, wherever]
I just tried an offering. I don't know if it worked or not.
if you felt the divine in your circle, or you felt something then you did it correctly. your first few times you might not feel anything [or it's so subtle you don't notice] simple things like you're happier, safe, or warmer, these subtle differences are how we tell if the circles cast correctly, or the Lord and Lady are presence. try meditating, think about the God then the Goddess and mark down if anything changed. could be a feeling, a sound, a smell, or a vision.
How do you know if the god or goddess heard you?
as i said above, you should feel them near you, if you do, then obviously they heard you. otherwise it could be something symbolic, say you place it outside and as you head back in you see a deer, or a family of squirrels come over to where you placed the offering. you could hear something, or feel something. it's different for everyone so it's hard to explain. i remember my first couple circles i was very nervous i did it wrong, i didn't really feel anything, i could hear them, or sense them. looking back though, i've always felt safe when i'm speaking with the Lord and Lady, or inside a circle.