IF funcation (maybe???)???

My second problem is this

I have a field called “Age”. What I want to do is;

If I type in the person’s age say “26” then I want another cell to display an age range (i need to entered the age ranges i want eg “16-20, 21-29, 30-39” etc. So if I type in 26 in the first filed I want to second cell to display “20-29”.

Again, any help??