Hi and welcome to the forum.
A few points which will make it much easier for you to get help here:
Please post in the correct part of the forum, many users will only look at certain sections, not many people look in the forum/web site section (which was the place you originally posted).
If you want help, please make it easy for people to help you by providing as much information as you can. Your project may be important to you, but it is not important at all to other forum users, so the easier you make it for people to help you the more likely it is that they will be prepared to give up their time to help you.
We need to know more about your setup to be able to help.
1. What version of leJOS?
2. What operating system? Is it 32bit or 64bit
3. Do you have the Lego software installed?
4. What version of Eclipse are you using and do you have the leJOS plugin installed, if so what version.
5. Have you installed leJOS on the NXT? Did you use the same system to flash the NXT, did that work?
6. What exactly are you doing, and what error messages are displayed.
Note that nn Windows/Mac you must be using a 32bit JRE *and* a 32bit version of Eclipse. Have you read the section of the tutorial about setting up leJOS? If not please take a look:http://www.lejos.org/nxt/nxj/tutorial/P ... tarted.htm