First off, what is Logical Volume Management and why do you need it? LVM is basically a set of hard drives grouped into being seen by the system as one hard drive. It is different than RAID, because there is no redundancy. In addition, the drives that are "grouped" can be of any size or any interface. You can have SATA, SAS, and IDE all in the same LVM. I wouldn't recommend it, but you could.
But what is it used for? Gigantic volumes, of course! Right now the largest hard drive you can buy is 3TB. What happens when you need a volume larger than that? You can use a RAID setup that will add redundancy, but you will also need a better controller and a lot more drives. But a simpler, quicker solution is to use LVM.
Here's the overview to get LVM going within Webmin:
Now for the nitty-gritty:
sudo apt-get install lvm2
Rackspace is another (awesome) option for a cloud service provider. I think their interface is extremely easy to navigate, and you have the added bonus of getting an external IP immediately instead of having to assign an external IP. The benefit of this is that your server, as long as it stays on, retains the IP.
So, go forth and create a Rackspace account! When you are done, come back and follow these instructions: