The Marine's Techwebs allow your battalion to purchases powerful abilities that improves the individual Marine capabilities.
In order for you to unlock them for your marines, head over to the tech control console to take command of the purchasing of Techs.
There can be only one Officer allowed to take control of purchasing Techs.
If an Officer outranking the current control wants to take over, they simply follow the instructions above, overriding the previous controller.
Head over to here to learn more.