Read value based on key from a web.config file

Hi All,
I am trying to create a function that can return the corresponding value from web.config based on the key provided
For instance, I have these values in my Web.config file:
<appSettings>   
    <add key="1" value="test1"/>
    <add key="2" value="test2"/>
    <add key="3" value="test3"/>
    <add key="4" value="test4"/>
</appSettings>
 How to get the contents from appsettings section into a collection so that I can loop through each item and read correct value record based on a key ?
any suggestions?
Thanks in advance .