New to your Atlassian account here or products ?
Atlassian has just too many super products to try.
Apart from their products, plugins make things more interesting to work on.
You can create TRIAL Account for JIRA and see how things work.
This manual contains information on how to use JIRA:
https://confluence.atlassian.com/jira064/jira-user-s-guide-720416011.html