Hello Sourav

Stenographer is an expert who can decipher English or some other language into a coded language known as shorthand and afterward reconverted it into the first language that too quick as 200 words every minutes. As there is not a particular diploma or certificate course you can join the Industrial preparing foundation to do a confirmation or certificate course in shorthand and composing.You can give SSC Stenographer exam which is organized by Staff Selection Commission to recruit eligible people for the post of  stenographer in central government organizations. I will attach some links which will help you more .

https://competition.careers360.com/articles/ssc-stenographer-selection-process

https://competition.careers360.com/articles/ssc-stenographer-preparation-tips

Hope this helps