Open the figures Library by default in a fold away menu on the left of your screen and load the figure you wish to clothe, then find the item of clothing you wish to use and click the add figure (double tick) icon. If its a conforming piece of clothing you will now need to go to Figure>conform to> (select figure name). Resources are DAZ3d, Renderosity Market Place, RDNA, PWFW, BBAY etc. you will find links to lots of free file in freebies section here and by following the links to the various sites on the webring - see far left of renderosity screen at bottom. There are Many many more which I havent mentioned such as SAMS3d, Poser Pros and so on :)