Good but not sure how to mail out

I got these postcards to send to my daughter in college. I sent the first one I filled in the address section put everything in the clear slave taped shut and added appropriate postage. it's been two weeks since I mailed it and she never received it. Not sure if that was due to the packaging. when I ordered these I thought that the postcard was going to be the record and then I was just going to be able to put that in the mail to her. I'm still not sure how to get it to my recipient.