Write down the fraction.
Choose a scale factor or use one that is dictated in your assignment. For example, you might want to dilate the fraction 2/3 with a scale factor of 3. This means that you are making the fraction three times larger.
Multiply the scale factor times the fraction. In this case, you would multiply 3 times 2/3. Write 3 as the fraction 3/1. Then multiply the numerators (3 and 2), as well as the denominators (1 and 3). This gives you an answer of 6/3, which can be simplified to 2.