For example, I added a field as Owner in IT service Management Incident creation page.I need to add or fill with multiple analysts names in that particular Owner tab. How to add that? Where I need to add multiple variables to get that?
How did you define the field in the Schema Designer? (I assume as an SREL to the cnt object). An SREL is only used to define a one-to-may (in this case, one contact to many incidents) relationship. If you need to define a many-to-many relationship (an LREL) then you need to create another object (table) that contains two one-to-many relationships.
Search the community for examples of creating custom LRELs.
you would need to implement something similar to this post
Multiple CIs on Request / Incident / Problem (CR to NR lrel/brel)
Retrieving data ...