[SalesForce] ExactTarget SOAP Request returns Fault in Response

This question is regarding using the ExactTarget SOAP API. I am trying to use the SOAP envelope sample given in http://help.exacttarget.com/en/technical_library/web_service_guide/technical_articles/creating_an_email_via_the_web_service_api/
I replaced the USERNAME & PASSWORD fields with appropriate values and modified the reference to http://exacttarget.com/wsdl/partnerAPI to the S1 endpoint link https://webservice.exacttarget.com/Service.asmx. When I post the SOAP envelope using the Chrome plug-in POSTMAN, I get a response back with a Soap:Fault that reads

WSE012: The input was not a valid SOAP message because the following
information is missing: action

What does this error signify and how do I correct this and proceed?
I am using POSTMAN to test the flow before I code the process in nodes.js

Here is the SOAP packet (As I said earlier, the USERNAME & PASSWORD have been replaced with my credentials and reference to "http://exacttarget.com/wsdl/partnerAPI" has been changed to https://webservice.exacttarget.com/Service.asmx. I took this SOAP Packet from the sample given on the example). I am doing the POST to https://webservice.exacttarget.com/Service.asmx

<SOAP-ENV:Envelope
    xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">   
    <SOAP-ENV:Header>
        <wsse:Security 
            xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
            xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
                <wsse:UsernameToken>
                    <wsse:Username>USERNAME</wsse:Username>
                    <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">PASSWORD</wsse:Password>
                    <wsu:Created>2008-07-02T13:01:11Z</wsu:Created>
                </wsse:UsernameToken>
        </wsse:Security>    
    </SOAP-ENV:Header>    
    <SOAP-ENV:Body>
       <CreateRequest xmlns="http://exacttarget.com/wsdl/partnerAPI">
            <Options/>
            <Objects xsi:type="Email">
                <ObjectID xsi:nil="true"/>
                <Name>Text Only in API</Name>
                <Description>Description</Description>
                <TextBody>Example email body for an email that is text only</TextBody>
                <Subject>Example Subject</Subject>
                <EmailType>Text Only</EmailType>
                <IsHTMLPaste>True</IsHTMLPaste>
            </Objects>
        </CreateRequest>    
    </SOAP-ENV:Body> 
</SOAP-ENV:Envelope>