The first step is to choose the paper. I have used both cardstock weight and lighter. I use these boxes most for candy etc. and I like the heavier weight better. It will work with just about any paper though.
Once you have the paper you will want to determine the size you want. I usually use a 12x6 size but any paper with a 2:1 ratio (8x4, 10x5 etc) will work. Obviously the bigger the paper, the bigger the finished box
Once your paper is cut you will want to mark the half way points on each side. Your first fold will be in half legenth wise.
You will then fold from the center mark on the width to the center fold of the paper. It is not a tricky fold but sometimes the paper will tear a little of your are too rough. Note that happened on mine but it is not really noticeable on the finished product.
If you wish to decorate the box, now is the time to do it. You can see where all the folds are and can embellish the box accordingly. Things like doodles or stamps can be put right over the seams and folds but thing like flowers or bling would be better on one of the flat surfaces.
Now the sides will overlap and you can use a hole punch at the center to punch a hole for the thread or ribbon to go through. I have done this both with and without using eyelets in the hole. If you choose to use eyelets, make sure that they are big enough for you to get the ribbon through. Also you do not want to seal the sides with eyelets as then you will not be able to put the items in the box.