The tab that you have bent up from the bottom piece is directing the water inside, not to the top of the bottom "J". By extending the sides down past the bottom, all water running down the side of the building (much more than the little bit on the top of the bottom "J") will be diverted to the outside of the siding. Reverse bend (on the inside of the J) from the side to under the bottom "J" Keep all the water moving down the side of the building. Do not channel it over the bottom.
The second picture shows what the water is doing now. By trying to channel the water to the top of the bottom piece, you are making it easy for the water to seep into the building. Extending the sides past the bottom will make it more difficult for water to enter under the window. 3rd picture.
Edit: I understand that it is running down the wall and under the siding. A little sealer in this spot which is a much smaller area to seal than the whole of the bottom of the window. When I built my pole barn, I put the side piece under the top and folded the middle of the top J over the middle of the side piece J. Ran the side down past the bottom J. This left only about a 1/2" of the siding where water could enter. I used NO sealer and have never had water get into the building under the window. Of course, our rains here might not be as strong as yours. Tomorrow I will try to get a picture.
Edited by Bmerf, March 11, 2014 - 09:43 PM.