How Do I Alphabetize Leads, Last Name First?

How Do I Alphabetize Leads, Last Name First?

I just imported over 1,000 leads of people who have already purchased at least one of our services. Now I want to follow up and obtain referrals. The leads show up in seemingly random order, organized only by date. How can I sort this list so it shows up alphabetically? This new user thanks you in advance.