Go to the dealer or mechanic of your choice and have him check the following:
1) Its an older car. Depending if its the original clutch on the car still, it may need to be adjusted or replaced if its grinding with the clutch engaged all the way. The clutch is not disengaging the flywheel, which its suppose to do for the gear.
2) Could be a problem with second gear. Have him check the gear. This would be more likely it if all other gears work.
Its one of those 2 things that I mentioned. Or your shifter might need some attention. As the car ages, its not as precise as it use to be.