Dnswl.org maintains a database of IP addresses (netranges) which are grouped into "DNSWL Records" (identified by a DNSWL Id, which is just an arbitrary number). This data is maintained through a combination of manual and automated actions - and by yourself.
Using the Self Service portal you can "claim" DNSWL Ids as being yours After verification you can then request changes to IPs already stored, or add new IPs. For most parts, there will still be an editor approval before changes take effect.
The Self Service portal is also used to manage the subscriptions which are required for certain types of users (eg for > 100'000 queries per day).