Begin by laying down on the bench with the dumbells resting on your stomach
Now bring the dumbells up to your chest, they should be pointing towards your feet and head rather than the usual position when performing chest press
Keeping your elbows tucked in by your side, slowly raise the dumbells above your head, until your arms are almost straight but avoid locking your elbows
Now slowly lower the dumbells until they are in line with your chest again
Repeat steps 3 and 4 until you can no longer maintain correct technique
Tips
Keep your elbows tucked in at all times, they should never point out to the side