Help with restore

Im having a little problem. First let me say im a total newbie as far as
sys-admin and such. Normally Im just a production guy. But as of late im
starting to have more responsibilties, backup, set up new clients, etc.
so please bear with me in my detail I just dont know what info you need
and what you dont......

I made a back up like this:
pg_dump -v -Fc -f bkp.tar.gz dbname

then I dropped the db
then I recreated the db
then when I tried to restore like this:
pg_restore -v -O -d dbname bkp.tar.gz

after I enter the password I get
pg_restore: creating FUNC PROCEDURAL LANGUAGE plpgsql_call_handler()
pg_restore: [archiver (db)] could not execute query: ERROR: function
"plpgsql_call_handler" already exists with same argument types
pg_restore: *** aborted because of error

however after looking back over my notes and the documentation that I
recieved I noticed that I was supposed to make the backup like this:
pg_dump -U dbname -v -Fc -f bkp.tar.gz dbname

Sincec this is apearantly a specific way to make the backup Im assuming
that that is why the restore doesnt work since it was setup do restore
form that specific backup syntax. What I would like to know is, how I
can get the data out of this archive, so that I can recover the data and
put it back in place and get the site up and running.

any suggestions?????

Thanks in Advance

Allen Smith