Hello @Niraj_Mukta welcome to the community!
as a brand new, highly welcome member, few limitations are available. You start as a Seedling and will be very soon promoted. Once promoted you will be able to send Private Messages and have further advantages:
- Send PMs
- Upload images and attachments if enabled
- Edit wiki posts
- Flag posts
- Mute other users
Please check out the post Getting Started with the MongoDB Community from @Jamie which will explain all this in much more details.
Hope this helps,
Michael