Do you mean downloaded figures and props, or tutorials? If it's items for use in Poser then as Lyrra says they have to go in the right places. If you look at the zip file containing the items there will be some things set to go in a folder in the Geometries folder in the Runtime folder in the Poser 4 folder, some things in a folder in a folder called Props, Characters, Hair, Cameras, Lights, Poses, Faces or Hands in the Libraries folder, and some things in a folder somewhere in the Textures folder. Anything in Geometries has to go EXACTLY where specified, or Poser will say it is running out of memory (you can edit things later, but the geometry is always least forgiving of mistakes). Anything in Textures should go where spcified, but Poser will either guess or ask if it can't find one of these items in the right place. The things in the Libraries folder are flexible (unless there is a geometry file, something .OBJ, in there which sometimes happens with stuff created with ProPack) in that you can put them in a different folder from that specified, but they must be in a subfolder of the library folder (Props, Characters etc.) specified. Not every pack will have every one of these - for example, props and hair often lack an OBJ file in the Geometries folder, and things often come untextured - but if the components are present you must follow the placemnt rules. Also, many downloads are add-ons that require something else - a texture to change the appearance of a piece of clothing requires that you have the clothing to start with, and most characters are for Victoria or Michael which are bought from DAZ3D.