Well first, do you know a bit about soccer?
Fifa is pretty easy to get into because the basic controls are enough to compete and have fun. When you get a better understanding you can really show of with the more advanced stuff.
For now if you are having trouble scoring try to lay of long distanced crosses in favor top of the box shots. The lob through pass works really well this year (LB plus Y) and you can use that to feed most of your runs to the box. Also dont forget that you can press forward on the right stick to play a ball in space instead of trapping it. This works wonders to beating center backs and getting a 1 v 1 against the keeper.
You can also put the game on assisted or semi assisted shooting. This will either automatically place the shot in the best area or at least give you the proper power and general direction for a good shot.
If all fails give the ball to C. Ronaldo, set the controller down and watch in amazement as he scores by himself!
EDIT: Also, (this is what I say when I coach my soccer team in real life) Placement over Power. If you are near the net make sure you dont hold down the shoot button to long or you will blast it over the net. Hold RB and press B for about half a second (1/4 the shooting bar) this will give you a instep shot which is far more accurate.