In a city-builder like age of empire, you need, like
@RangerX said, to focus on every part that composes the game.
First, you'll probably agree with me, you need to understand how to move a player ( or an unit ) with the mouse using point-and-click style.
Then, you probably will want to avoid obstacle so you'll enter the wonderful world of pathfinding (NOT). Once you can move around and avoid stuff
as you move from point A to point B, then you'll probably want to try moving multiple units at the same time. In age of empire, you can select
more than one unit and move them all in formation. That's another tricky part.
When you're confident with the moving, then creating the city-building part is a whole other different experience.
You need to be able to "place" a building, add a "build time", add "upgrades", etc.
If you attack each and every parts one by one, you'll be able to get over the huge mountain.
But if you look at the tip of the huge montain and start running toward it, surely you'll put your feet in a hole that was right in front
of you which was quite obvious.
I suggest that you take small steps, and making sure you have a solid footing before taking another step.
Slowly but surely, you'll eventually reach the top of the montain.
Regards,
CedSharp