I think we need more information to help you. Can you post a pic of what you've done so far? Have you already pinned the sandwich?
All seam allowances in quilting are 1/4", even for borders and binding unless you like a wider binding.
Ironing seams must be done for the top and the bottom before they are sandwiched. Many people do not like the tediousness of this step, but it's huge to me to get the seams going in the right direction when they are inside the sandwich.
Not sure if that answers your question.