use loft command, select the sketch4 firstly (please click on shown place while selecting)
secondly select the sketch 5 ( please attention that to click on shown place. it saves you from errors)
1. click on guide curves box 2. click on shown spline 3. confirm that
now select this spline and confirm that
make same things for the other two lines
lofted body is ready
use mirror command
use fillet command
open a sketch on the front plane
draw shown lines..
try to make your sketch like in the picture. please note only the shown lengths.