What type of information does the TIFF file contain? In case it is multispectral imagery, you would have 3 or more bands and that would require a classification first (see: Understanding multivariate classification—Help | ArcGIS Desktop ), before you convert the raster to polygons. If you have a single band data (but no continuous surface) or a little number of "classes" you can convert the raster to polygons (shapefile) using Raster to Polygon—Help | ArcGIS Desktop
