Understand that Life Cycle phases of a project are different from the PM Process groups.

Watch the video : https://www.youtube.com/watch?v=XDO5bhU1BA8

Then brainstorm, and identify what could possibly be the Life cycle phases. Use the Phases which you identify as the Level 1 in your WBS. Elaborate on the detailed activities of your project as you move down in the WBS. Draw the WBS using an application such as MS Word, MS Excel, Visio,