This is wrong:
> $ cd /usr/share/pgsql/contrib

The first cd should be something like:
cd /usr/local/src/postgresql*
or maybe:
cd /usr/src/postgresql*

If you don't have either of those directories, then you haven't installed 
postgresql from source, and you need to do that before installing postgis from 
source. Installing from RPMS would be a good option.

Chris






