Buying OEX

It looks like OES will not dip below 567. I decided to purchase a bull put spread of 560 and 565. Buy 560 at $0.65 and sell 565 at $1.10 for a net credit of $0.45. I am not sure how to enter the order in. According to the mannual, I will need to enter a negative #. I entered -0.45. The interest for this trade is 45/455, which is about 10%. Breakeven point is $560.5 (565-0.45).