what is the use of "wgetrc" command in wget download
The first command simply specifies an alternative configuration file to use instead of the default ~/.wgetrc. You could also specify it using --config=/hom1/spyga/spp/wgetrc_local as argument to wget.
This file can contain wgetrc commands that change the behaviour of wget. In this case it's probably done so user and passwords don't have to be supplied on the command line. Specially on multiuser systems it is a security risk to pass passwords on the command line, as that can possibly be viewd by other users, so it's a little better to store them in a file with restricted access permissions instead. This way only processes started by the owner of the file can access it.
Another use of the wget startup file is to change it's default settings, user agent etc...
It's all documented here.