Skatebiker:

Well, to configure repositories, you need to run:

Settings/Application manager

Then pick from the menu:

Tools/Application catalog

Then create/edit as you see fit. However, perhaps you have all necessary repositories already. Just to prove the point, I removed my own 'python2.5-gpsbt' and then re-installed it (from a terminal session, while logged in as 'root', of course):

Nokia-N800-23-14:/usr/lib/hildon-desktop# apt-get install python2.5-gpsbt
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
python2.5-gpsbt
0 upgraded, 1 newly installed, 0 to remove and 97 not upgraded.
Need to get 0B/38.7kB of archives.
After unpacking 131kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
python2.5-gpsbt
Install these packages without verification [y/N]? y
Selecting previously deselected package python2.5-gpsbt.
(Reading database ... 17647 files and directories currently installed.)
Unpacking python2.5-gpsbt (from .../python2.5-gpsbt_0.1-18osso2_armel.deb) ...
Setting up python2.5-gpsbt (0.1-18osso2) ...

What happens if you try the same thing?