A poster session is an opportunity for you to share your research in a creative, visual way. Visitors (other students, professors, community guests) will walk among the posters while you give a brief (1-3 minute) talk about your research and answer questions.
A poster session is the presentation of research by an individual or members of a research teams. Typically a separate room or area of a professional or academic conference is reserved for the poster session where researchers accompany a poster, illustrating their research methods and outcomes.
The best way to start the design of your poster is to look to others for examples. Don't be afraid to emulate the style of others, if you see something that works, use it!