I need a custom registration page from for my site. I want to take some details from my regular visitor and then finally want these details in a csv or excel file. Is there is a plugin which can do this for me just like we have Contact Form 7 for Contact Page??? This question may seems common but please consider me as i am very new to wordpress.
If I understand you correclty, you are essentially asking two questions.
For one, you are looking for a solution for a customized registration- (login- / profile-) page. Also, you want to export data to .csv or .xls
As for the first issue, I'd recommend taking a look at Jeff Farthing's excellent Theme-My-Login plugin.
As for the second, I know of one discontinued plugin that might be of help. I have no experience with it though. Check out ALO Export XLS. A dirty solution would be to export directly from the DB via phpMyAdmin or the like. You might have to write your own plugin for this issue.