Hi Asha,
First off, it's probably best not to store your
Java project files in the java/bin directory as it can get pretty full, and also you won't get to experience the full fun of classpaths unless you deploy code outside of you Java directory
In answer to your question - are you compiling in the correct directory? (in your post I noticed that you stated two different locations in which your temp1.java file was)
If your temp1.java file is the C:/jdk1.5/bin/myproject/classes/a/first/ I would make sure you are located in the C:/jdk1.5/bin/myproject/classes folder and then try executing
Best wishes,
Daniel