I have only the USB cable so can I charge it with my laptop or computer or any other way?
You might get a small trickle-charge by connecting to a Windows laptop, better if you don't run the iPad whilst doing so, but only a Mac is capable of recognising & supplying the higher power requirement of an iPad.
Connected to any standard USB port on a PC, the device will claim it is not charging - though in practise it will eventually manage to charge it, it will be very slow.
Your best bet, if you don't own a Mac, is to buy a dedicated iPad charger.
Yes, plug it in your laptop/desktop and it will automatically charge your ipad.
No, Most laptop usb ports will not have sufficient power to charge a full sized ipad. You will need a high-power usb port. However you should be able to charge from a desktop computer but it will take longer.