best what you can do is follow chapters (step by step) of documentation for Jira linked below.
while you will have some theoretical background you should install your own Jira (you can install it on your local, but I recommend to use normal DBMS and not HSQL).
After you will feel comfortable with many administration areas (several months) then you can start learning on Atlassian University (https://www.atlassian.com/university) and after one or two years try to get certifications (https://www.atlassian.com/university/certification).
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