With out wanting to sound condesending or rude, you have got to learn race craft...
The question of how to get past is either to,
Get on the gas earlier,(out of the corner)
Get on the brakes later, (into the corner)
Get the track position to put your self in an overtaking position.
Apply pressure to force the other fella into a mistake.
You also have to choose the right moment - make the other guy think.
If your opponent is running a blocking line - as in oval racing, by staying on the white line, and theres no way you can get the inside line, then your out of luck.
You need to do the following.
i)Take an earlier pit stop, and be faster after the pits.
ii) beat him in qualifying so you get higher up the grid and dont need to pass him on the track,
If all else fails you have 2 other choices....
1) the pit manouver.
2) Give up son, you aint cut out for racing.