Tiling, Rasters and geotiffs

[Kieran Ames]

Hello List.
I've begun learning about geotiffs and rasters and such.
Is there anyone who could talk about tiling multiple 1:24000 quads as a
basemap? I can't find anything in the archives on how to do this.
Example: I have shape files that cover different themes for Long Island,
NY.
roads.shp
lakes.shp
buildings.shp
These individual shape files cover the whole of Long Island.

Now, I found planimetrics of Long Island, but can't figure out how to
point to the one appropriate to where the user has zoomed in to.

Thanks,
Kieran