You can multiply any number by 1 and not change its value. Now there are many many ways to write 1, like 7/7, -9/-9, .456/.456, etc.
The two fractions have the denominators as 6 and 9.
Write out the (or think of) times take for 6 and 9 and look for the FIRST common factor. The answer is 18.
Now how do you go from 6 to 18? You multiply by 3, so you multiply (11/6) by (3/3).
Same idea for other fraction.
You CAN NOT add fractions until the denominators are the same!