How to integrate two application.

See What an awesome answer. I think it applies here too. You can't just say "integrate the two application" and expect it to be easy. Murali helps you to realize it is not so easy. I think two things that should be determined is the screens and the database, as Murali indicates. You can start by designing the new screens. Then you need to design the database. We don't know if the formats of the tables for both applications are the same or if the tables are different formats and if so how the data is related.

Making babies should be easy, but sometimes integrating a man and a woman together into a family is not as easy as we might expect. Integrating applications can also be difficult.

Please post the queries with proper explanation to resolve it quickly.

1) You said that there two applications . Does the applications are web /windows applications?
2) Integration means you want just import the data from one app to another app ? 
3) Do You want to integrate the screens?
4) What are the features that you want to integrate ?
5) For doing the integration what is the common key factor?