Something Smells Fishy

Well I bought a fish yesterday. Purchased a 10 gallon tank and cool little decor for the "habitat". Sad thing was Petco only had one goldfish left. So, that was the little guy I got. Brandi named it Bella. I have no clue if it is a male or female. I don't even no where to begin to find out how to tell. So, we are making an educated guess of girl. Here are some pictures of the tank.