Hi Laurie,
If you have anymore questions after reading the tut's on Plug-ins let us know ok!
Ok now for the presets..they are like Shelleyrae said, they hold a set of information to create a certain type of effect to the image you are working on.
Presets are available to brush tips, shadows, textures, bevels and many others. You can apply a preset to almost every effect that you use under the effects menu. There are many presets available for PSP and they are sort of like styles in PS.
You can find some presets here by visiting the links
http://www.psplinks.com/content/Presets_Downloads.html also a search on google will bring up even more.
Of course when you download presets, you place them in your presets folder, and I am sorry to say this folder of mine is a mess, as I do just place them all in there loose!!
hth's and have fun with another area of PSP!!
