How to make RAID1 on running ubuntu 12.04

Question

I want to make RAID1 on a running linux

I installed the Ubuntu server 12.04 Then, I installed the backuppc software. I installed the OS on a HDD with 160GB of storage

So, I want to put another 2 x 2TB HDDs to store those backup data. So, how can i make RAID1 to those 2 TB HDDs?

I mean in 160 GB HDD, I installed the OS

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      499711      248832   83  Linux
/dev/sda2          501758   312498175   155998209    5  Extended
/dev/sda5          501760   312498175   155998208   8e  Linux LVM

Then, I put 2 more HDDs namely sdb1 and sdc1

information about /dev/sdb

Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000f2e02

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048  3907028991  1953513472   83  Linux

Information about /dev/sdc

Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x0005d662

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048  3907028991  1953513472   83  Linux

So, My idea is that I want to save the data inside the /dev/sdb1 and want to make /dev/sdc1 as the mirror of /dev/sdb1 (with raid1)

So, how can i do this?