How to change iphones if one of them doesn't have a sim card?

I have a verizon iphone 4, it doesn't have a slot on the side for a sim card. My sister gave me her also verizon iphone 5s, but it needs a sim card. How can I use the iphone5s one if my iphone 4 doesn't have a sim card or it's inside?

Go to a Verizon store and have them help you.

The 5s doesn't need the SIM (at least for calls/texts), but for data use, yes.

A Verizon rep should be able to help