This is a simple steps to build your own FTP server in your home/ small office network, with username and password to access it. I run this on my Ubuntu Jaunty (9.04) server edition:

1. Installing the pure-ftpd package:
#sudo apt-get install pure-ftpd

2. Creating new group for FTP users:
#sudo groupadd ftpgroup

3. Creating directory for FTP users:
#sudo mkdir /home/ftpusers

4. Creating directory for each FTP user:
#sudo mkdir /home/ftpusers/joe

5. Creating the user in linux system, include the user in ftpgroup and point the home directory:
#sudo useradd joe -G ftpgroup -N -d /home/ftpusers/joe/

5. Create default password for FTP user:
#sudo passwd joe

And you are done! :)

* This example using "joe", you can create your own username.