Linux Expert - Ubuntu Disk Space problem

System hostname *.*.*
Operating system Ubuntu Linux 9.04
Webmin version 1.530
Time on system Mon Jan 24 15:56:41 2011
Kernel and CPU Linux 2.6.28-19-generic on x86_64
Processor information Intel(R) Core(TM)2 Quad CPU Q8300 @ 2.50GHz, 4 cores
System uptime 0 hours, 20 minutes
Running processes 137
CPU load averages 0.01 (1 min) 0.04 (5 mins) 0.05 (15 mins)
CPU usage 0% user, 0% kernel, 0% IO, 99% idle
Real memory 7.37 GB total, 173.18 MB used

Virtual memory 486.30 MB total, 0 bytes used

Local disk space 274.60 GB total, 21.13 GB used

Package updates All installed packages are up to date
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I have around 253 GB of free space, I also checked via TERMINAL, I got this:
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root@afghans:/var/www# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda6 4.6G 3.3G 1.2G 74% /
tmpfs 3.7G 0 3.7G 0% /lib/init/rw
varrun 3.7G 124K 3.7G 1% /var/run
varlock 3.7G 0 3.7G 0% /var/lock
udev 3.7G 164K 3.7G 1% /dev
tmpfs 3.7G 0 3.7G 0% /dev/shm
lrm 3.7G 2.5M 3.7G 1% /lib/modules/2.6.28-19-generic/volatile
/dev/sda5 76M 20M 53M 27% /boot
/dev/sda8 266G 188M 252G 1% /home
/dev/sda7 4.6G 3.8G 604M 87% /var

Why does it say 87% & 74% used while I already have 253 GB space available and why am I not able to upload files and start MYSQL?

Anyone who knows how to allocate the free 253 GB into these folders and remove the errors of starting my SQL and unable to upload the files can bid, please.

Thank you,
William