add a search bar on a page and limit it to search only under post titles? I wand to add a search bar on a page called "dictionary" and want to limit it to post titles. I mean it should search only texts in posts tiles not the whole posts contents. Please explain me clearly step by step how to do it. 

Regards
Ismail
Use custom_search module.

By this module you can create customize search form that searching on custome content type and custome fields on content type.