Hi,
I believe this is the high time to show what you can do by using your skills and ability. Though you are a fresher as you said above, but still are selected and provided a chance to work with your employer and your Boss expecting you to perform, i would say you must search option that can help you in performing or using your skills instead of taking much stress with these things.
Also the people who have selected you, are very well aware of your qualification, skills and that you don't have experience (fresher) but still they trust you and expecting you to perform means you have a good opportunity to learn, to apply your knowledge.
Solution:
-The very first thing that you have to do is to make a note of all whatever your is Boss asking you to do.
-Discuss the same with your colleagues and friends who are with the same work profile (in & out side of office)
-Read the documents, threads and available material related to assigned task on this place.
Lastly, I request you to share what actually bothering you here as you haven't shared such details except your Boss's high expectation because until you share your problems, community wont be able to help you in your problem properly.