I am renting a dedicated server with Parallel Plesk on it (which I hate and I try to use command line).

I have a filesystem that is full,"df -H" prints this:

Filesystem             Size   Used  Avail Use% Mounted on
/dev/md1               4.0G   4.0G   361k 100% /
/dev/mapper/vg00-usr   4.3G   1.4G   3.0G  32% /usr
/dev/mapper/vg00-var   4.3G   2.8G   1.6G  64% /var
/dev/mapper/vg00-home
                       4.3G   4.4M   4.3G   1% /home
none                   1.1G    24M   1.1G   3% /tmp
tmpfs                  1.1G      0   1.1G   0% /usr/local/psa/handlers/before-local
tmpfs                  1.1G      0   1.1G   0% /usr/local/psa/handlers/before-queue
tmpfs                  1.1G      0   1.1G   0% /usr/local/psa/handlers/before-remote
tmpfs                  1.1G      0   1.1G   0% /usr/local/psa/handlers/info
tmpfs                  1.1G      0   1.1G   0% /usr/local/psa/handlers/spool

The server I'm renting has 1TB of hard drive. Why are these so small, how can I increase my storage ? (I'm pretty beginner with Linux).

Thank you