I have 105.

The paddles just behind the brake levers should move the chain from bigger to smaller sprockets. The left one for the front, the right one for the rear.

To go from smaller to bigger sprockets, you have to push the brake levers themselves inward. The right controls the rear gears, the left controls the front.

It's hard to tell exactly what's going on. The small paddles behind the shift levers should feel pretty firm and give a loud click. If they feel like they move too freely and don't click, you've gone as far as you can go and need to shift back the other way by pushing that whole brake lever inward. Again, don't shift when the chain's not actually moving.