that's not really the best way to ask for help, maybe your post was lost because of all the recent spam bots' attack.

you can use fapman "faster application manager" instead of the stock one, it is much faster and more flexible..

but incase you insist of modifying the repositories, edit the file:

/etc/apt/sources.list

and add your repositories there..

please note that entries you write there can't be managed by the application manager, meaning it will use those repositories but you can't delete or rename them without editing the file again..

entries are in the form of:

deb url distribution components

example
deb http://repository.maemo.org/extras-testing/ fremantle free non-free