have tried to get maps from online games i've played to use on my own (not pass them a long).
but i don't get it to work.. can anyone explain?

an explanation of how to do custom stuff as putting in a custom flag and then use it would be much appreciated 2.

thanks.

c:\Program files\team17\Worms Armageddon\Users\Games

Go to there (or where ever you installed the game to) and right click a *.wagame file and choose to extract the map. It will be stored in c:\Program files\team17\Worms Armageddon\Users\SavedLevels

but i can't find them in-game :(

http://worms2d.info/Colour_map#Using_colour_maps

an explanation of how to do custom stuff as putting in a custom flag and then use it would be much appreciated 2.

Go into your Worms Armageddon folder. Then go into the user folder. You should find a number of folders in there. Among them are the "Flags" folder and the "graves" folder. Any custom flag you make must be 20x17 and have 256 colours. Custom graves must be 24x32 and have 256 colours.
EDIT: Obviously, you must put custom graves in the "graves" folder and custom flags in the "Flags" folder.