I am trying to create Force.com project with Eclipse but It's not successful.
Although Nick's comment already told you that you need to input your security token, I guess you are still confused about how to find it.
If no one in your current team knows your security token, which I believe is your current situation, just reset it. To do this, follow this guide: https://help.salesforce.com/apex/HTViewHelpDoc?id=user_security_token.htm . Then you can use this security token for your Eclipse login.