Take your tape and tape the card closed, so you cannot open it. You might want to sign your name inside first. If you want to enclose the recipe for your cookies this is the time to do it. You can write the recipe inside the card or tape the recipe to the inside of the card. After you have taped your card together you should be able to gently squeeze it to form a cylinder.
Cookies can be any kind, but it is much more personal to make homemade cookies.
You may make any kind that you choose. Perhaps you have a favorite family recipe that you would like to use. It is important that when making your cookies that you do not make them too large to fit into the Cookie Card cylinder. I have found it best to make cookies that do not spread when baked, this way you can be in control of the size that you want. I then make a ball from my cookie dough and lightly tap it with the bottom of the glass.