<p>I'm looking for a way to find a the windows login associated with a specific group. I'm trying to add permissions to a tool that only allows names formatted like:</p>

<pre><code>DOMAIN\USER 
DOMAIN\GROUP
</code></pre>

<p>I have a list of users in active directory format that I need to add:</p>

<pre><code>ou=group1;ou=group2;ou=group3
</code></pre>

<p>I have tried adding DOMAIN\Group1, but I get a 'user not found' error.</p>

<p>P.S.  should also be noted that I'm not a Lan admin </p>

OU is an Organizational Unit (sort of like a Subfolder in Explorer), not a Group, Hence group1, 2 and 3 are not actually groups.
You are looking for the DN Attribute, also called "distinguishedName". You can simply use DOMAIN\DN once you have that.
Edit: For groups, the CN (Common Name) could also work.
The full string from Active Directory normally looks like this:
cn=Username,cn=Users,dc=DomainName,dc=com
(Can be longer or shorter, but the important bit is that the "ou" part is worthless for what you're trying to achieve.