I have the "critical updates available" in my edit task plane.  I click it and am redirected to the DNN site.  How do I know what updates I need to download?  I'm not directed to a specific download.  I'm new at this and obviously need more guidance.  Someone help me out.

you need to upgrade the dotnetnuke installation.

in Host settings, check for the version you are running. If DNN 4.x, upgrade to DNN 4.9.5, if running DNN 5, upgrade to DNN 5.1.2

Backup all files and database. stop your site or set "autoupgrade" to "false" in web.config file using a text editor

Download appropriate source package from dotnetnuke.codeplex.com, unzip hierarchically into DNN installation folder, overwriting existing files.

set autoupgrade back to true and browse your home page.

Shelia,

sorry for any frustration with DNN, but like any server software, installation and system maintainance requires some knowledge beyond the desktop experience. there are a couple of hosters, which provide DNN turnkey ready and maintain installation, to allow you to concentrate on the content, but if you have to do it yourself, you should know about windows server and IIS applications.

Regarding your questions, I don't know about your hosting situation, which determines all actions beyond DNN - including backup. A production site has to be backed up frequently, please ask your hosting partner / administrator about details.

Editing web.config requires a text editor, like famous notepad.exe. search for "autoupgrade" and you will find a line with

AutoUpgrade = "True"

you need to alter to 

AutoUpgrade = "False"

(I wouldn't ask my 80 years old mother to do it, but I am sure, you can handle it :))

HTH