If the denominators are different,then
1.Find the least common denominator (which is the least common multiple of the denominators)
2. Multiply each denominator by a missing factor to get the least common denominator for each fraction.
3. Multiply the numerator by the number from step 3 and place this number over the least common multiple.
4. Add the numerators of the two fractions and place this over the least common multiple.
5. Simplify the fraction.
This video should help with adding fractions.
When multiplying fractions you simply multiply straight across and simplify the fraction.
This video should help with multiplying fractions
Finally, I created this simple GIF file to review the steps for dividing a fraction.