Hi Neha,
First of all, I need to know whether your project pertains to a particular department or the whole organization. Anyways, what you can do is:
1) Design a questionnaire depending on the department/s you are going to interview. For example, if interviewing the HR department, you can use HR jargon and terms in your questions, whereas any other department will require being asked in layman's language.
2) Once your questionnaire is drafted, select a sample of employees to interview. Take a mix of employees across the hierarchy.
3) Interview them, get their feedback, analyze each interviewee, and try to figure out if he falls in the satisfied or dissatisfied category.
4) If your sample is large, use software like SPSS or any other statistical software, or else work manually on the statistics.
5) Also, look into exit interview forms and try to find out reasons for people leaving the organization.
6) Finally, make a presentation with the various statistics, suggestions from employees, and your own recommendations.
All the best.