I would like to create a new custom dashboard using the built-in application overview dashboard, if anybody having expertise on creating dashboards using built -in please help me on the same.
Depending on what screen you are referring to theres a couple options here.
1. Main monitoring page
This is the screen that shows the transaction flow with a breakdown of web/mobile/visit requests. To best replicate that screen i recommend you use the transaction flow dashlet
2. Application overview
There is no way that i know of to replicate that application overview screen, the best option i can think of is selecting the particular transaction in that application overview screen and drilldown to the business transaction. there is an option to take those baselined charts and add those to any dashlet.
So from the applicaiton overview page, there is no direct way to copy that view into a custom dashboard, but there are a couple options to get some of those views into a custom dashboard. Hope this helps.