You have to first have 5 planets not including your homeworld, Dead class or U classes you can either explore (below are the steps) or attack people to get the 5 planets
Click"Build Ships"-> Click "Viator" ->Built 25 of them
Then click "Explore" and start exploring for 6 planets now you got new planets to work with do the same and built Housing,Agriculture and commercial on them.
(Warning: Remember to click "Manage Fleet" and Disband/Destroy all your ships after you found the planets by typing the amount of ships you have in the boxes and then press "confirm")
Then click"Project"
click"colony upgrade"
click"colony cluster 1"
click"confirm"