How do I upgrade units in afterwind?

So I would like to know how to upgrade units (marines if you need to know what type).
Thanks,
Luke.

There is a 'Upgrade' button in the right upper corner when you logged in the game. There you can buy all kinds of upgrades, with the SP you earned.

Check: http://www.afterwind.com/home/faq.php?faq_id=5 for how it works.
Check: http://www.afterwind.com/forum/topic.php?topic_id=2657 for available upgrades.