Well Dave2112 and Khali probably know a heck of a lot more than me as they are the real experts but let me give it a shot as I am a newbie as well. I do have Poser 5 so that things might be a bit different.
On the right hand side is a bar like thing, click it, and you get a bunch of folders for things like figures, props, expressions and the like.
To add a prop open up the prop folder and click on a prop and then click on the check mark below to add it.
To add a figure repeat the above only open the figure folder then pick a figure and click the check mark to add it. If you have a figure and wish to add another then click the double check mark.
To change expression click on the figures head open the expression folder and then pick a expression and click the check mark. The face should change expression.
To get a pose click the figure, open the pose folder, pick a pose, and click the check mark.
For beginners like us goto
www.daz.com for more poser files for sale,
www.renderosity.com for advice and more poser stuff for sale,
www.renderotica.com for more sexy poser stuff for sale and forums to get advice,
www.thralldom.org for kinky bondage poser stuff for sale and forum advice, and
www.darktoys.com for kinky stuff for sale for poser as well.