Parkes is right about the double-sided tape. Also, you might want to try using the Tombow Mono Multi liquid adhesive in the green and white bottle. You can run just a tiny line about 1/4" inside the edge of your layers and it will hold well.
I used it when I first started making cards and liked it. Then I moved on to the ATG gun which rolls an adhesive onto your cardstock. It's my favorite of all to use.
And a warm welcome to SCS and this wonderful hobby!