after completing the task on the trailhead..they are saying like 'we couldn't find this field'

Hi Omkar,

 Make sure you are creating this field as a given Name and as a given type of trailhead Challenge.

 you can complete this challenge after watching this video :

 https://www.youtube.com/watch?v=Jo-ZzWp8C_U

 If you find your Solution then mark this as the best answer.

   Thank you!

   Regards,

  Suraj Tripathi