I have been using the USB plug to upload sketches in the Arduino/Genuino 101. As I have no idea about batteries and how I could power up this board for outdoor use, I researched online but became really confused and afraid I might fry the board.
Please suggest how could I power this board ( which external battery is suitable- i am so confused). I think it needs less than the Uno.
According to the specs, the recommended input voltage for an external power supply is 7-12VDC; a power supply with the capability of 500mA or greater will be fine.
Yes, you can use a battery. However, in both cases (the battery or the external power pack), you MUST supply power via the 2.1mm DC jack OR the pin labeled as VIN; doing otherwise bypasses the on board regulator and will damage your arduino.