This is actually pretty easy to solve. First, you have to make both fraction have to same denominator (the number on the bottom). Next, you add the two fractions. I have the steps written below.
2/3 + (-1/6) Write Original Problem
(2)2/3 + (-1/6) Make the denominators the same by multiplying the first fraction by 2
4/6 + (-1/6) Now add the fractions
The final answer is 3/6, which can be simplified to 1/2. I hope this helps!