Check out this American English at State graphic explaining one of the suggestions you gave us -- "whether" and "if." 

In general, IF is for conditional sentences (If it rains, I won't walk to work) and WHETHER is used when there are two options (She hasn't decided whether to go to the movies or go out to dinner). 

However, they often can be used interchangeably. Take a look at these rules about using WHETHER and practice by writing us a sentence with WHETHER!