I have a 96 saturn and it's my first car and I don't really know much about cars... neways my oil was completely empty and I didn't know until my car started making this knocking noise... so I put oil in and my tail pipe started smoking... should I be worried? And if so how much will I have to pay for repairs?

Tell us exactly how much oil you put in there and what's it reading on the dip stick now?
Has the knocking gone away?

No it hasn't my dad said it was the rod so basically I need a new car