ashu888ashu888 has nicey described it in his first post. I never had problem with free kicks as i play football and know what it takes to swirl a ball so could easily make out in fifa what to do only the problem area is the power to be applied. If the free kick isin a angle then keep a low power and aim in far corner opposite to where keeper is standing, so that when he jumps to save it he puches it invainly to put it in his own goal. For swirl use SHIFT button to right or left swirl and keep the pointer of ball in 45degrees downside at the corner of ball( dunno how much u can grasp from it).
. Try it and let me know for further queries>