You can check if your mango is ripe is by smelling near the stem end - it should have a strong fruity odour. If you don't smell anything then it is probably still not ripe.
You can also check if your mango is ripe by gently squeezing it - when you apply light pressure it should be soft. If the mango is still hard then it isn't ripe enough yet. If the mango is squishy then it is overripe.
The colour of mangoes varies based on the variety - it is best not to go by colour to determine if a mango is ripe.
Once ripe, mangoes should be moved to the refrigerator, which will help keep them fresh but should be eaten in about 5 days when ripened.