Long Division Method
Many of us were taught the long division method to divide large numbers. This process can be very confusing but there are all kinds of neat Long divison foldables to use to help kids remember the steps. You can find so much readily on division that I won't bother to list resources for that.
Tip: Have you students use graph paper for long division problems to keep the work in order (it's helpful for all the operations really). I found some Free Division Graph Paper at eachers Pay Teachers - several different sizes to choose from in this pack.
Alternative Method
If your student has mastered the times tables or can compute quickly in their head, check out the quick, short division method. It was revolutionary for one of my kids.