data logging operation

In my project, I need to store the pressure ranges as well as when the motor is started and shut down by the arduino using a datalogger.can anyone suggest me how to do this

Try using this thing (SerialGhost module)

It is a serial data logger that is quite cheap, easy to use, and works well. Just buy a TTL to RS232 converter and hook it up through the Tx Rx pins of an arduino.

You then save data as ASCII characters using the Serial commands we are all familiar with.

It depends entirely on what you don't know, and the absence of any detail of the situation and intention suggests that is quite a lot. If you do know how to acquire the data, all you need do is send it to a proper terminal programme and record it there. If that is inconvenient, you can record it locally to SD card, and I believe there is an example of that in the IDE.