Find a hosting software board that you will be comfortable with using. If your educational institution has one, use that. Otherwise there are a number of free and paid programs on the web that will let you create your own discussion board. If you lack experience in programming, pick a software program that is intuitive and that is designed for beginners. Many boards are nearly "plug and play" while others will require you to provide extensive programming to design your own elements.
Read the tutorials closely so that you understand the ins and outs of the software that you have chosen. Read the FAQs provided on the host's site. You may also wish to visit a board where other admins talk about how they manage their board.
Go to the admin control panel. Name your board and set up controls for who can access the board, post on the board, read the board or make changes. You will have the option to make the board available to everyone or only your students. You can also set up particular areas or sections in the board that only particular students have access to, making the board a useful tool for group projects.
Create appropriate forum titles based on the subject of your board and what you want students to discuss in it. For example, for a class on Jane Austen, you might have one section for "Sense and Sensibility" with specific topics within that section being discussion questions on that book. You could have another section on "Influence of Bath on Austen's Work" or "Austen Biographical Notes" or "Austen's Literary Influences."
Post a topic explaining the rules of the discussion board. This post might include rules like no flaming and no sharing of essay question answers or even a mandatory number of posts per week.
Send students invitations to join the board at their email address or give them instructions in class on how to sign up for the board. Check in frequently to approve membership requests and monitor the board's discussions.