You're too busy building just your economy.

There should be a statistic-screen from your current game in the upper right corner where you can see what you are best at and what you are worst at. Being the 16th in military is a bad sign in a 16 player game. I try to be at the top 4 usually so the AI thinks twice before attacking.

also if you allways agree to every "open borders"-treaty the AI will just scout your area and army and decide if it has bigger force than you.

Best allies are the ones who aren't next to your borders, because they will be less tempted to attack you because of the distance.

I love Fire Emblem to death. Civ4 is better.

I picked up Civ4 complete long with Bioshock, Prey, Freedom Force and a whole bunch of other awesome games (Bradi!, Sid Meir's Pirates0 for about 50 bucks. I beat you.

Also civ 4 Complete is 50% off on Steam right noow. Or it was up until 3 hours ago...

Well, I have no problem staying alive I must admit. My culture usually rocks other nations away, since I am too advanced for them to try anything. The point is that you need to expand fast and a lot. If you develop those cities, you can specialize. either you go for every city has every advancement, or either you go for several cities produce soldiers like crazy, so you can fend off invaders. You have to take into account that certain areas are better for developing soldiers than others. CIties in open space usually have less "hammers" meaning they can develop more slowly. If you're near mountains, those will provide more "production", meaning you can pump out soldiers (and structures too) faster, but it also means that the food coming into that city is lower, meaning it will grow slower (lower population => less people working the land => less production as well). So it's taking care of that balance. The cities have to be able to grow, but production centers will usually go slower than others, but they are vital though.

What does "extremely low difficulty" mean?
There are like 8 difficulties, I didn't ever move beyond the third, but it is perfectly normal. If you suck at the first one, there might be something wrong. Also, on this level, usually I declare war on other civs, not backwards.

Did you play the tutorial?
Do you make as many new settlements as you can?
Do you make workers who improve the tiles around your city?
Do you chose researches that will help you in your plan? (military for conquest, culture for cultural dominance, etc)
What are your points? You can watch them above the minimap. Early in the game, you might be smaller, but in easier difficulties, you naturally improve faster than your enemies. Attack those that are smaller than you.

It's a lot better in replay value in any case.  What with all the different mods and such... each game being completly different.

As for why you might be sucking....

Do you have technology trading on?

Because if you have technology trading on but don't get in early on the technology trading you get screwed as a few nations start trading technology left and right with each other creating themselves as technological overords that far surpass everyone else.

I always make a beline for the tech that allows technology trading... if i don't turn the option off... which i usually do since it's more historically accurate.  Nations weren't about to be giving away their state secrets to each other.

I must have so not seen that option, but where is this technology trading option? I know I make natios kill each other and bleed themselves because of just one or two special tehnonlogies.

When you start a new game under "Custom Game" you can turn off technology trading.

You have not provided enough information to allow us to guide you in the right direction.

That said, turn off tech trading. It is an option when you start a new map and see if that doesnt help you learn the game a bit. All this will do is slow the cpu down a bit more giving you a chance to explore the game more fully.

Another thing to look out for is combat positioning. I cannot stress how important tactics are when it comes to combat. Whenever possible you want to build cities on hills and fortify them with walls and other defenses. Also remember that the longer you fortify a position with a unit the greater their defenses will become up to a certain point. Conversely, never attack an enemy that is sitting on a tactically favorable position such as a forest, jungle, or hill unless you have overwhelming odds. Lastly, take note of unit strength and weaknesses. For instance, you do not want to attack spearmen with horse units. Along the same lines, always check the odds before attacking and use various different units on defense to gain unit advantages against attacks.

That should get you through the easy difficulty. You still need to learn to micromanage cities, land plots, and resources.

I disagree with that. African militia has machine guns, China has communism, and the USA has video games, even though neither of them invented these. 

I always found it more unrealistic that medieval and modern civs could live near each other, and even after centuries, the more primitive one would be unable to at least partially reproduce these technologies.

They can reproduce the technologies... but it takes time.

Machine guns didn't reach africa until well after they were useful etc.  Hence the having to do it yourself seems to better represent the "following" of techology.