1. Open your Windows DNS Manager.  (Start Menu -> Administrative Tools -> DNS)
2. Expand the nodes on your DNS Server and select the target domain where you will be adding the two DKIM TXT records:

Right-Click the target domain and select "Other New Records...":

Scroll towards the bottom of the list and select "Text (TXT)" then press the "Create Record..." button:

In the new "Text (TXT)" resource record, enter the following:

1. Record name: _domainkey
2. Text: (This should be the value of your DKIM Policy Record).
   Example: o=~; r=postmaster@yourdomain.com

Press "OK" when you are done and you should see an entry similar to: 

DKIM Public Key Record Instructions

1. Open your Windows DNS Manager.  (Start Menu -> Administrative Tools -> DNS) 
2. Expand the nodes on your DNS Server and select the target domain where you will be adding the two DKIM TXT records:

Right-Click the target domain and select "Other New Records...":

Scroll towards the bottom of the list and select "Text (TXT)" then press the "Create Record..." button:

In the new "Text (TXT)" resource record, enter the following:

1. Record name: (DKIM Selector)._domainkey 
   Example: ue201008._domainkey
    
2. Text: (This should be the value of your DKIM Public Key Record).
   Example: v=DKIM1; p=MIGfMA0GCSqGSIb4DQ(.....)z2nJSPOxvGGznkcY25w5lIYpxpVwZ/IwIDAQAB;
   

Press "OK" when you are done and you should see an entry similar to: