Several resources you can use to learn more - 2 are here; Click on "tutorials" then "Poser" via the link at the top of the page. Click on "Poser Forum FAQ" two lines below the "Welcome to the Poser Forum" line above. A really good site for more info is RonKnights.com - Ron writes terrific tutorials with the complete newcomer to poser in mind - LOTS of screen captures! Read the manual that come with Poser, It's not well thought of overall, but it has a lot of the really basic stuff. (downloadable version available at Curious Labs website, as well (link at top of margin of this page). To address your main problem more directly - to Double-click on a clothing item tells Poser to REPLACE the current character. Also if you highlight the item and click the SINGLE-checkmark below. The DOUBLE-CHECKMARK tells Poser to ADD the selected item to the scene. You'll then need t6o conform them (if it's clothing you're adding - see tutorials or manual for how) to make them pose with the character. The manual will tell you how to use the mouse for posing as well, but most find the dials are incredibly better once you get used to them. Welcome to Poser, and have fun!