We have web-based application using asp.net and tridion. In Tridion I have a have an existing form, with dropdown and textareas. I want to add Upload button in trdion form component itself. Is it Possible to do so , or better should i add the upload button in asp.net User Control. Please suggest me ASAP, as i'm new to the tridion.
I'm going this part of your question:
"I want to add Upload button in trdion form component itself"
From this i'm assuming you'd like to add extra functionality to the SDL Tridion GUI.
There's a lot of content out there to help you create GUI extensions, I'd recommend reading these posts, in order:
https://sdltridionworld.com/articles/sdltridion2011/tutorials/GUIextensionIn8steps.aspx - if you'd like to add a dialog to your cms page, it's possible to have your .net page as part of your extension.
Google is your friend, there's a bunch of great GUI extension posts out there :)