[clueless]

I am new because I need some help and thought someone here might be able to provide some answers. I have misplaced my IPHONE. I don't think anyone has found it because there have been no calls made on it since my last call on Thursday. Now the battery has died because calls go directly to voicemail. I am scared to tell my husband so I thought I could hide it by purchasing a new one on ebay. Well it arrived yesterday and it doesn't have a sim card. I KNOW....I am an idiot. Can someone tell me what to do in case I never recover my original new IPHONE? Thanks. I really feel bad, so you don't have to go on and on about my stupidity. Obviously, as my name says, I am clueless about technology.