I am a hobby photographer and sell images, will I need to pay taxes on what I make?

Ok, here is the deal. I am a hobby photographer, I sold a few images to magazines. This is the first year I have done this and have made $840.00 dollars income. I will be filing jointly with my husband. I am sure I will have to claim this income, but what would the taxes be on the $840.00. Can you make up to... show more Ok, here is the deal. I am a hobby photographer, I sold a few images to magazines. This is the first year I have done this and have made $840.00 dollars income. I will be filing jointly with my husband. I am sure I will have to claim this income, but what would the taxes be on the $840.00. Can you make up to so much and then just pay on the remaining? What is the usual persentage rate for such a small amount?
Update: Sorry, I forgot to add that I live in the US.
Update 2: All the answers so far have been great. But I am not really "Self Employed". This is just a hobby and I happen to make some money at it this year. Surly you all don't mean that I will have to pay all of that has been mentioned, if so, then it is not worth the trouble of even trying to sell photos.
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