Many users are at first puzzled by PadKeys because it actually operates more like a regular computer keyboard that you might find on your laptop than a traditional mobile telephone keyboard. To access symbols like '@', '!' or '()', you don't need to go through the process of tapping a '?123' or other special key to get into an alternative layout where keys for these are shown. Instead you just tap one of the 'Shift' keys on the lower left and right (labeled with an up-arrow as on many keyboards) and these symbols will be found in their regular places where the number keys are.
If you prefer, you can also set PadKeys to display these symbols on the keys themselves at all times by choosing PadKeys Settings (long-press Globe key, then slide finger without lifting to the Gear, then release) and turning on the "Show Shift Hints" option. (The screenshots on the App Store for PadKeys show what this will look like, as well as how the Shifted keyboard looks when this option is off.)
Our video here shows all of this in action.