Pickers pick the avocados hard and allow them to ripen later at the grocery store. This way, the fruit retains its freshness for as long as possible. You should be glad that your avocados are not too ripe, so you have more control over the level of freshness.
To ripen the fruit faster, get a tight plastic container, place the avocado inside and seal the top tightly. As the fruit ripens, it releases ethylene gas, which increases the rate of ripening. You could also throw in other fruits that give off this gas, such as apples and bananas.
Follow the same steps if you have a brown paper bag instead. Fold over the top to prevent the gases from seeping out. Whether the fruit is ripe or not, store the bag or container in a dry, dark area.