Prerequisites for Generating a burn down chart

I need to generate Sprint Burn down chat in Jira

Why do you need to do this specifically, rather than your team?

1. what is the difference between story point field and story point estimate field

Have you asked your administrators what their intention was when they set up these fields?

2. When this is to be updated so that the burn down is properly reflected as per what is actually happening in sprint

An information radiator, such as a Scrum Board, should tell the truth at all times. Each team member should ensure that the progress of work is kept up to date, and that there is an accurate projection of work remaining.

This is based on my knowledge of Jira and I do not claim to be an expert. 

In case you haven't read this you should.  

https://support.atlassian.com/jira-software-cloud/docs/view-and-underst…

Notice these points

Before you begin

• The Burnup Chart only applies to Scrum boards

• Story Points on sub-tasks are not included in the Burnup Chart. (Only Story Points on parent tasks are included.)

From what I understand the estimate field is not used at all for any of the Jira Scrum reports.  They are all based on the Story Point field.  But the type of item you choose when creating it is important.  The charts mostly report on Stories with some including Bugs and Tasks.  But Subtasks are not accounted for on any of the reports to my knowledge.  You have to make sure that the items you are using to indicate work are tied directly to the Story and as they are completed, the % complete will be indicated. 

Hi Ian .. yes discussed with the admin team. Didn't get any satisfactory answer. After some R&D found this gets reflected properly when:

1. Story point is updated in the stories and then the stories are assigned to any sprints.

2. The status of the stories needs to be updated regularly by the developer , this will reflect the chart properly.

Hi Daniel yes the article is helpful...thanks ..

After some R&D found burndown gets reflected properly when:

1. Story point is updated in the stories and then the stories are assigned to any sprints.

2. The status of the stories needs to be updated regularly by the developer , this will reflect the chart properly.

Will keep in mind the below points you mentioned.

The Burnup Chart only applies to Scrum boards

Story Points on sub-tasks are not included in the Burnup Chart. (Only Story Points on parent tasks are included.)