TL;DR. Having looked at your save I think it's really worth a look at the two links I posted above as these contain much better more concise information than I can write.
I think the main problems in your game are trying to work out where is best to put your cities, possibly the order of researching technologies and definitely what to build in your cities.
If you press 'Ctrl + y' you can turn on tile yields. These will show you food
, hammer
, and commerce
of each tile. In addition 'Ctrl + r' shows special resources such as pig or iron - sometimes you need more technologies to reveal some of these. As a rule of thumb for an absolute beginner, never settle (place a city) on a tile that has more than 2 food
or a special resource (there will be a lot of exceptions as you get better at the game.) Putting your capital on the pig tile was a big mistake - pig, riverside corn (wet corn), and fish are the best tiles in the game in my opinion. Having said where you put Beijing was wrong, it's hard to say where you should have put it unless you post the turn zero save.
If you double click on a city you can see which tiles it is working - the ones which have circles around them. You can choose to work a tile by clicking on it in this view. The population of a city determines how many tiles can be worked. Each city can only work a 5x5 grid of tiles with the corners missing - you can turn on tile grid with 'Ctrl + t' - so the rice by Beijing that you have improved can never be worked unless you put another city near it. Tiles that are not being worked by a city contribute little or nothing to your game - the rice woudl help if you put a road on it as it is a 'special' resource that would give you health but the cottage 3 south of Beijing will never do anything for you unless you put a city nearer to it which can work it.
Building 5 workers was really good as they are the really key initial unit but I suspect the reason you lost 3 of them was moving them into the bit of the map you can't see (fog of war.) Never move a settler or worker into the fog of war as they are incapable of fighting and will be destroyed by any enemy unit (except scouts, other workers or settlers as these units can't attack.) It's really, really good that you haven't automated your workers as the computer is terrible at telling them what to do.
Workers are the key unit and the key priority in your first city is improving it's food resource. Unless you start on the coast (resources in the sea have to be improved by a fishing boat not a worker), it's best to build a worker first in your first city and aim for a first technology that enables your worker to improve a food resource within the 5x5 (minus corners) diameter of your city. After this, key technologies are bronze working (enables the slavery civic which enables you to trade population for building things quicker) and writing (enables libaries which helps with research and 'open borders' which helps with commerce and diplomacy.)
Almost all buildings are pointless - you've built a lot. Key things to build in the early game are workers, settlers, granaries and libraries. You'll need a few units for keeping cities happy and to escort workers/settlers through the fog.
Playing at cheiftan your game is probably still very winnable from this position if you were to settle on the ivory ASAP, build 10 catapults and 10 elephants (nothing else in the interim) and attack a neigbour followed by another, and another.
Probably the best way to learn is to post a save from turn zero and wait for advice on how to progress - this is called a shadow game. If you decide this is something you'd like to do I'll aim to contribute but I only get a night a week or so to play so might be a bit slow. If you decide to do this, it's best to start a custom game, choose 'panagea' for map type, turn off huts and events but otherwise leave all the settings as standard (i.e. map size and number of opponents.)
I hope some of this is useful and not too simple for you. Civ 4 was my first civ game and I remember it being very difficult at first but you will get better quickly and it's really rewarding when you do. Please keep us posted on your progress.