error building deb package of pctel modem source

i tried to build the deb package from the tar.gz of pctel for debian sarge (2.6.18-4-686). but i got the error as shown below. can someone tell me what went wrong here. can u help me build this package?

i got the pacakge from linmodem 'pctel-0.9.7-9-rht-7.tar.gz'
debian:~# cd /usr/src/pctel-0.9.7-9-rht-7
debian:/usr/src/pctel-0.9.7-9-rht-7# dh_make

Type of package: single binary, multiple binary, library, kernel module or cdbs? [s/m/l/k/b] s

Maintainer name : root
Email-Address : root@debian
Date : Wed, 26 Mar 2008 10:32:35 +0530
Package Name : pctel-0.9.7-9-rht
Version : 7
License : blank
Type of Package : Single
Hit to confirm:
debian:/usr/src/pctel-0.9.7-9-rht-7# dh_make

Type of package: single binary, multiple binary, library, kernel module or cdbs? [s/m/l/k/b] s

Maintainer name : root
Email-Address : root@debian
Date : Wed, 26 Mar 2008 10:33:00 +0530
Package Name : pctel-0.9.7-9-rht
Version : 7
License : blank
Type of Package : Single
Hit to confirm:

Currently there is no top level Makefile. This may require additional tuning.
Done. Please edit the files in the debian/ subdirectory now. You should also
check that the pctel-0.9.7-9-rht Makefiles install into $DESTDIR and not in / .
debian:/usr/src/pctel-0.9.7-9-rht-7#

please explain teh process of building a packge from source in detail.