Hi Surabhi,

-As per your requirement there is a guide that you can follow to learn about salesforce administrator certification ,see the link below:

1.https://www.masonfrank.com/salesforce-blog/salesforce-admin-certification-guide/

-Or you can follow proper steps given by salesforce that are:

1.Review the Study Guide. Visit https://trailhead.salesforce.com/credentials/administrator and download the free study guide. 
  Look at the test outline and review each topic. If you don't know answers then look up the answers in Salesforce Learning Center and you will find the answer.

2.Trailhead.  This site from Salesforce has all types of training.  https://trailhead.salesforce.com/home

3.Watch Video Tutorials. We would also review all the video tutorials in your Salesforce org. These are frequently updated and provide a
  great guide as to the type of questions that will be asked.  We have found that many of the questions are pulled directly from these tutorials so pay close attention and take notes if needed.

4.Focus on What Matters.  Remember that the test is weighted based on each section so use the 80/20 rule when choosing what topics to study.
  For example, when I took test 17% of questions were on Customization, 13% were on Security and Access and 13% were on Analytics. Focus more time and energy on sections that will give you the biggest bang for the buck.

5.Give Yourself Time.  Studying for the exam is not something you want to do in one day or one week.  We would recommend budgeting at least one 
  month to absorb the concepts discussed in each test section.  Allow for one hour per day to study and then increase the number of hours as you get closer to the test date.

6.Skip and Review.  The test is 60 multiple-choice/multiple select questions and you get 90 minutes to take the exam. Our advice is to skip
  any questions that you don't know an immediate answer and review after you have answered all other questions. 

7.While the number of questions can seem overwhelming at first, a little preparation can go a long way in increasing your odds of passing the test. 
  Remember to stay calm, cool, and collected as you are allowed to take the test 3 times so don't sweat it if you fail the first time.

8.Get a Coach.  akaCRM offers personalized 1:1 training and coaching in blocks of 4 and 16 hours. Consider purchasing some time to ask questions or to get training.

9.Register for the Exam.  We always tell people, we guaranty you won't pass the exam if you never register for it. Go ahead and register today,
  even if it is for a session 2 months in the future. Deadlines tend to help us all get things done.


I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too.

Thanks and Regards,
Deepali Kulshrestha
www.kdeepali.com