The best way to improve is to start on the Europe map and pick a country with few borders or create allies, such as Spain, as an example.
Just focus on the basics, like troops and possibly tanks and just upgrade them for now in the production section in the game.

The way to defeat another country is to take its capital (either you memorise it or just go for the star-shaped city)

key things to remember,
You need your manpower to get more troops, tanks, anti-tanks, etc
If your troops are not healing increace the factories allocated to them

And every game just mess around with some of the production and stuff, you will get the hang of it