You can make some changes in your order until it gets "In progress" status.
If you want to add a product, change a colour or amount of ordered goods, please enter your account and click on the order you would like to modify. Then just add a note with the modifications you would like to make.
If you decide to add a lot of stuff to your order, please place a new one with a note "Merge my orders". Please notice that it will increase the order processing time.