i am starting to study FLEX. i have only flex sdk. So can i start study only using that. If so please suggest me the link to go through..
But still, Using an editor
If you're on Windows, see if you can run mxmlc.exe (the compiler) from a command prompt. Create a simple Example.mxml file to test it out.
mxmlc.exe Example.mxml
Here's a simple Hello World mxml source code.
Easy steps are well documented on Adobe's site and in chapter 2 of "Flex 3 in Action"
Flex Builder will be the very best way to learn as its got a debugger and thus lets you step thru code see how it works. FlashDevelop is free tho it lacks a debugger - still very useful
You can certainly build application with solely the open source Flex SDK. I have posted some instructions for using only the Flex SDK on Linux. If you are on a different platform the instructions can be slightly adjusted.