What index to refer and what queries to be written if i want the following data related to dashboards?

[monyathomas]

1. List of dashboards sorted by username viewing it
2. Successful user login details on the splunk to be presented as graph

[adonio]

many man y answers in this portal around these subjects
short answer: _audit and _internal indexes
here are 2 links that will help you moving in the right direction:
https://answers.splunk.com/answers/386889/locate-when-users-accessed-dasboard.html
https://answers.splunk.com/answers/694105/how-can-i-see-who-viewed-the-results-in-a-dashboar.html

good luck