How do you upgrade weapons?

From your home planet, select ‘weapons’, you will find that you start with a bazooka and a grenade, both at level 1. To upgrade or learn new weapons you need a certain number of crystals and metals, the combination and numbers required for the next upgrade is listed below each weapon.

Once you have enough crystals and metals to upgrade your weapon of choice, select ‘Research’. Research a weapon takes some time, if you have more friends with the application, the research time can be smaller, as there are more friends to help you research. However, if you do not wish to wait for the research to complete, you can always click to ‘upgrade now’, but this will cost Playfish Cash.