Web Forms :: How To Search Content Through Files

Basic Concept :

1. User will upload files into system. {say into Database or storing in some location (C:/temp/.....).}

2. Suppose user wants to search file/s which contains particular keywords - suppose user wants to retrieve files which contains word :

Finance Management. System should return all the files which contains that word.

I know how to upload file and retrieve file of particular name.

Problem : Only need idea of functionality in which key word will be searched through the several files and search result will return names of the files which contain that word.