Take a look at the strategy part of this forum. In particular, look for the older posts. Start with Dread Lords as the expansions can be even more overwhelming.

Also, go to the galciv2 wiki, you can google it or find it somewhere on this site.

Some basic strategy tips:

- population is key in this game, but watch out for your morale, always keep it at 100% in the beginning as you get a nice bonus for pop growth.
- start with a morale buidling on every new planet, do not build to quickly as it can ruin your economy very quickly.
- make sure your diplomacy and military ratings are high up as this will keep angry races off.
- Make sure that you find out how the economic system works (sliders etc..) It's rather different from other strategy games.