There are 2 ways to create a lead.
You can either "Create a Lead" from the Sales>Leads screen using the "Create Lead" button.
OR you can create a lead from a Company record using the Create Lead button.
This will open a new lead screen. Simply fill out all the relevant details on the form and hit the Create Lead button to add the lead to your pipeline.
As you can see below, lead #4 for Shiny Glazier has been added to the pipeline until the inital "Lead" stage.