Basically, using JMeter consists of the creation, configuration and execution of test plans and the analysis of their results. Test plans are sets of requests against local or remote servers (or clients) configured to run by following specific instructions.
In the configuration of a test plan you can specify several input and output parameters and you can configure the basic conditions that should be met so the test plan is successful or not.
JMeter test plans are composed of different components. Here is a list of the most important ones with instructions about how you can add them using the JMeter UI and what their purpose is: