@kiran-ravin It's a lot to answer this question in one community post.
If the organization already has other data sources storing the data of Infra and Software, we can bring into CMDB through Discovery or Service Graphs. It involves various phases like Planning, Ingestion and Maintenance.
Once you have the CMDB ready, you can use Service mapping to map few services and monitor their health.
The CSDM comes into play when you are ingesting data in the right tables.
There are many courses offered in Servicenow University. Please go through them to get an understanding of CMDB and CSDM.
We can't summarize all of them in a single post.
