Insert the new fuel line into the hole toward the center of the tank. (it should be pretty tight, but not too hard to push through)

Keep pushing the fule line until it comes out through the gas cap. I used a needle nose pliers to pull it through.

press a fuel filter on the end of the fuel line (see picture with white cylinder)

pull the fuel line back out through the hole so that the filter is setting mid-way on the bottom of the tank.

Make sure you are using the fuel line that fits through the two openings tightly so that if the trimmer is tipped, no fuel leaks out.