Thunderbird is an Email Client Software and you can work with it in the following way.
1. Open Mozilla Thunderbird.
2. In the left panel you can see a list of your email accounts. Double Click on "Inbox" or if its hidden, click on your email, and it will expand and show the inbox, the trash list. etc. **
Anther option is to right click on the email and click on "Get Messages**".
Thunderbird also automatically checks email every 5 to 10 minutes. It also automatically checks mail when you open the program.** **