Back up a farm by using Central Administration
1. To perform this
procedure, you must be a member of the Farm Administrators group on the
computer that is running Central Administration.
2. In Central Administration, on the Home page, in the Backup and Restore section, click Perform a backup.
3.
On the Perform a Backup — Step 1 of 2: Select Component to Back Up
page, select the farm from the list of components, and then click next.
4.
On the Start Backup — Step 2 of 2: Select Backup Options page, in the
Backup Type section, select either Full or Differential.
Read More:
http://www.dshift.com/blog/using-central-administration-to-back-up-a-sharepoint-foundation-2010-farm/