These instructions were written for Microsoft PowerPoint 2010. The directions may vary depending on the version of software you have.
There are many other programs that will help you design an effective poster, such as Adobe Illustrator, Mac Presentation, or even Google Drive Presentation.
Read a short presentation on poster design and theory that also has lots of great examples of creative posters.
Generally scientific posters follow a similar structure to academic papers:
Outreach and class project posters may have different sections.
Poster design is as much as it is art as it science. Most sites will tend to agree on general poster design, although there are a few areas where they deviate. In all cases, think about "WHY?" before you put anything on a page.