Assuming that registering means saving data in order to be able to view the same graph later, you have to decide first if you need to use a graph or chart (to do this, play with graph/chart examples and see wich one is good for your application or let us know about what do you want to display on that graph/chart). After, you can choose one way of saving data, writing to file:
- as binary data
- as string, after conversion
- as waveform
Hope this help