Hi Chandan,
That's a lot of questions. Let me take them one at a time and see what I can do...
how to caputre record creation in update sets?
If you are referring to meta data (like incidents), you can add these. The best way is to use the list UI action "Add Application File" as you create a scoped app. That will result in those records in an update set.
how to create many to many relationship?
Very easy. Creating a Many-to-Many Relationship - ServiceNow Wiki
what are globel br ?
They are typically used for global functions, however they have been superseded by script includes.
how to establish one to many and many to many relationship blw two tables?
One-to-many are done with reference fields. Many-to-many are described above. (repeat question?)
what is one to many relationship in Snow?
Again, reference fields are used to relate one field on a table to another record in another table. Reference Fields - ServiceNow Wiki
