You can also use the System Map screen(F3).  Right click on the planet you want, a drop down appears with four options, mouse-over the last one (populations) and a create colony option is displayed.

I tried to send a Weno team, but the game said I needed a population.  Is there another way to do that than to move colonists around? (That planet is far away and got toxic gases in its athmosphere. )

In the System Display screen (F9) click on the planet in question and then click on the add colony button along the bottom of the screen should do it for you.  You only need to designate the planet with a colony, it does not need to have any people there at all.

Brian

An Engineer Brigade actually.  You'll find them under ground combat units not teams.

To create a Xenoarcheology team you will need to go to the Population and Production Screen (F2) and then the Teams/Academy tab.  In the upper left there is a pull down menu for the different types of teams.  Select the colony you want them to be at first(or you will need to give a ship orders to move them to the planet where you need them) and select 5 officers with hopefully the best ratings in Xenoarcheology (xeno for short).  Once they get on a planet with ruins they will start trying to figure out the background info that the engineers need to actually do the work.  This can take anywhere from a couple of weeks to a 8-10 years (I think I had one that took 11 years but can't quite remember)  Once they figure out the language you will see the description on the summary page (F2 screen) change from having a bunch of ?? marks to a name of the original empire, a tech level (1-5) and how many installations are available to attempt to recover.  When this happens then your engineers can get to work activating them.  Be warned that many of them will not be recoverable, and the engineer's commanding officer's xeno rating does help.

Brian

You have to send an archeology or geology team? dont remember wich one. once you get basic information such as the ruin name THEN engineer will start working on the ruins.

Ruins are the remnants of older civilizations. You need a Xeno team to decipher the language, and Engineering units to recover any stuff that is still functional.