A 
system for building a 
database that stores information representative of the organizational structure of a 
community of users of a 
computer network is disclosed. The 
system uses an 
online computer applications service that facilitates the 
initiation and completion of transactions between users in the 
community. Initially, a first user from the 
community registers on the computer applications service and information representative of the first user is stored in the 
database. Next, a first transaction 
record is created in the 
database from information inputted by the first 
registered user. The first transaction 
record includes at least one field representing an identity of a first unregistered user in the community, a field representing a role of the first 
registered user in the first transaction, and a field representing a role of the first unregistered user in the first transaction. After creation of the first transaction 
record, the first unregistered user is invited to register with the service when information representative of the first transaction is sent to the first unregistered user. In response to this invitation, the first unregistered user registers with the service and information representative of the first unregistered user is stored in the database, thereby transforming the first unregistered user into a second 
registered user. After registration of the second user, further users from the community are invited onto the service and registered on the database by repeating the above process.