Evergreene, after you move the mods to the Mods directory within NWN, yuou then start a new game, and go to the 'Other' section of the menu...

All of the mods that you have placed in the 'mod' directory will be listed there, as well as a description of what the mod's objective is....

Quite nice and easy set up for playing the mods...

Now, you will also be able to play with existing saved character, or you will be able to create new characters, just for the mod... The mod description will let you know what level character is best for the mod. Most of them I found, at least for single player, suggest level 1-3 characters...