There should be a file named fstab in /etc/
I would use CIFS rather than NFS.
automounts.xml should look like:
<?xml version="1.0" ?>
<mountmanager>
<fstab>
<cifs>
<mount>
<active>True</active>
<hdd_replacement>False</hdd_replacement>
<ip>10.0.0.3</ip>
<sharename>threetb</sharename>
<sharedir>threetb</sharedir>
<options>rw,utf8</options>
<username>flyingscotsman</username>
<password>flyingscotsmanspassword</password>
</mount>
</cifs>
</fstab>
</mountmanager>