First of all, you never import migrations
. It is not a module to import, it is a command tool to execute.
Second, migrations were introduced to Django in 1.7 version and you say you are using 1.5 so you won't be able to use it.
Before Django 1.7, people used to work with South because South gives you the ability to make migrations in databases. With Django 1.7 you don't need South anymore because migrations are already included in Django. In other words, South was included in Django in version 1.7.
Take a look at this link: https://docs.djangoproject.com/en/1.7/topics/migrations/
They explain that they included migrations into Django.
Actually, the last version of South is version 1.0 and they announced they won't be releasing more versions because they are working on Django 1.7 version where South was included. They will support current version but they won't add more features.
Take a look at this link: http://south.readthedocs.org/en/latest/releasenotes/1.0.html
They explain that 1.0 is the last major release of South because they are working on Django 1.7 migrations.