Car is knocking

Have you checked the oil?

Yes it was low so I added a couple of qts but it's still knocking

And so it will continue to knock as the rod bearings are bad now.

So does that mean that the motor is blown

No it is not blown yet, but would be if you keep driving it. If the car is in good shape, and you want to keep it you may want to consider a rebuilt engine. Looks like you would have around $3400 into it, buying the engine and having someone put it in. Or you could get a junk yard engine, lot cheaper.