Copy and paste this code into the page you want to show disk information for your web server:

<p>
<?php
// set partition
$fs = "/";
// display available and used space
echo "Total available space on this partition: " . 
round(disk_total_space($fs) / (1024*1024)) . " MB\r\n<br />"; 
echo "Total free space: " . round(disk_free_space($fs) / (1024*1024)) . " MB\r\n<br />";
// calculate used space
$disk_used_space =
round((disk_total_space($fs) - disk_free_space($fs)) / (1024*1024)); 
echo "Total used space: " . $disk_used_space . " MB\r\n<br />";
// calculate % used space
echo "% used space: " . round((disk_total_space($fs) -
disk_free_space($fs)) / disk_total_space($fs) * 100) . " %";
?>
</p>

That should produce something like this:

Total available space on this partition: 38195 MB
Total free space: 18464 MB
Total used space: 19731 MB
% used space: 52 %

Howto display uptime information like:

Time since last reboot: 43 days, 12 hours, 13 minutes , 45 seconds