Suppose the Disk is /dev/sdb, the second scsi disk,
create as many partitions as you need using command n
Label them with command t as 8e for making it Linux LVM
Write and Exit with the command w.
Format the partitions you require using mkfs command
mkfs -t ext3 -c /dev/sdb1
vgextend VolGroup00 /dev/sdb1
lvextend -L 15G /dev/VolGroup00/LogVol01 ;for extending LogVol to 15GB
lvextend -L+1G /dev/VolGroup00/LogVol01 ;for adding one more GB to Logical Volume LogVol01
lvextend -l +100%FREE /dev/VolGroup00/LogVol01
Next you shall need to resize the filesystem.
resize2fs -l /dev/VolGroup00/LogVol01
Thats it finished Njoy :) !