In game, there are five resources: Arms, Steel, Coal, Oil, and Food.

Arms maintains your current military's supplies as well as helps to create new soldiers, tanks, etc. The only way you can obtain arms are as follows:
- Buy them from Global Trade (Under Finances)
- Build a Munitions Factory in a City and begin to produce them (some cities already have them, and you can begin producing them from there).
Steel is a resource that you must obtain from the regions you own, or from trade (it is assumed that all resources may be obtained through trade). Not all regions have steel available to harvest. Under "Region Production" you may expand your metals production by creating a metals pit or mine. Eventually, you may research more efficient mays to obtain these quicker.
Coal, Oil, and Food are essentially the same - you obtain these resources by harvesting them in available regions (almost all regions are capable of producing food, so long as you have a farm, plantation, or the like).

However, each time you attempt to build a metal/coal mine, oil well, or farm, it requires Manpower, measured in MPUs. MPUs tend to only accumulate over time - some think this happens exponentially. The longer you wait, the more MPUs you will get each turn. [For example, if you had literally 0 MPUs after building many things, you would have 100 or so by your next turn (as a major power, anyway) If you continue to wait, next turn you may have 210, and the turn after that 340, and so on.] You can build medical centers inside your cities to stimulate MPU growth. Others argue that MPUs rise at a constant rate, with a couple ways to increase it. One of those ways being simply to expand your territory, others to increase IPUs in neighboring cities. Nevertheless, MPUs can be considered a double-edged sword. With more improvements, programs, and factories you make, the less MPUs you shall have. Adequate Food Supply is also necessary for MPU growth.

Still, cities don't produce things quickly. Some cities only produce large buildings 20-40 turns at a time. This can be fixed. A city has an IPU rate, which measures its productivity. Larger cities will have greater IPUs. To increase IPUs, you must build factories. The more you build, the faster cities may be able to create things. [Another example: A city with, say 5 IPUs will require AT LEAST 40 turns to build a Mechanized/Large Factory. After the long wait, the IPUs will jump to something like 20. After that, A Factory may only require 15 turns, increasing IPUs of the city to about 40, and so on. Eventually, you can get cities with IPUs of 150 or greater. By then, large buildings and powerful units can be built in a matter of 1-5 turns.]

However, you cannot constantly be building: you will lose money.
To make money, sell some of your resources if possible (This can easily account for 20-25% of your revenue if you are a Major Power like the United States)
Otherwise, you will need to produce something in a city.
"Goods" are the cheapest thing you can produce, and do not require resources.
Some things, like Textiles, Petroleum, and Appliances cost resources to produce, but can create a larger yield of revenue.
Once again, the amount of money produced is determined by the cities' IPUs.
Therefore, it is crucial to balance your need to expand with your need to produce.

This is relatively simple. A city you own can produce military units like soldiers, artillery, tanks, fighters, and naval units. However, some of these take time to acquire.

Things like tanks, aircraft, and advanced infantry require reseach some of the time.

In order to conduct research, you must have a university (which can later be upgraded with a research facility).
- Air Force Academies are required IN THE SAME CITY WHO HAS A UNIVERSITY in order to research the specifics of air units.
- Nuclear/Chemical Labs are required for Chemical and Physical Research
- A shipyard is required to produce ships... you get the picture.

After you have researched your desired units, such as (let's say) tanks, you must make sure that you have the proper buildings to produce them. A Vehicle Mechanization plant is required to produce most vehicles, an Air Base AND Building to create planes, and so on.

Keep in mind that some units have a greater Attack or Defend counter than others. Early tanks are efficient on the offensive, but a single division of infantry can defend far more effectively.
You can increase your defenses in a particular region by building earthworks and concrete bunks (also AA guns and shore batteries...)

Simply produce a couple waves of soldiers, planes, tanks, artillery, or any combination of what ever you feel, then move them into enemy territory. If their collective strength is greater than the enemy's defenses, they tend to win and claim the territory.
The land you conquer is only considered yours if it wasn't invaded by the enemy (If Germany Invaded France, and you land in Normandy, that land goes back to France, who had it first. BUT if you are able to move into Berlin, which was held by the Germans, the land becomes yours, as it was not previously invaded.

This is a small guide, because much is learned by DOING. If you have any questions or requested amendments/ additions to the guide, consult the forums or send me a message.

If you need more details, the manual, which is available on the Library page, is substantially more in depth and helpful. Be prepared for plenty of reading.

Enjoy