Start by drawing a circle representing yourself then draw lines off the circle and add circles to the lines. Fill in the name of the alters (if you know them) and connect them together. All my SRA alters are at the top and are all connected. Some alters are only connected to me and some might be only connected to one other alter, such as Mary and Andrea in my example.
If you are still new in your diagnosis you may have a lot of empty circles. Don't be discouraged they will be filled in as you progress in your therapy. It's taken me 12 years to be able to completely map my system, but that is not to say it will take you that long. Everyone is different! This is only one way to map your system. You can come up with different designs of your own, such as triangles or squares. It doesn't really matter how you do it but it is important that you do it. Knowing how your alters all fit together can give you key ideas on why and when they were created. It shows the relationships between each of the alters and perhaps what their role in the system is. The inner map will change, over time, too. Some alters may fragment off into another alter, or if you are planning on integrating some of the circles will be joined into your main circle. If you are working on co-consciousness some of the circle may be closer to you or the lines shorter.
Give this a try and keep your map handy, such as with your therapy notebook or journal. Decorate it, doodle with it, whatever you want to do. It is your map! Hope this brings you a greater understanding of YOU!