Amadauss - sorry this thread has gone a bit off track with banter!
Your original switch has only two black wires, the hot coming in and the switched hot going to the light. The timer however also needs a neutral, so that it has both hot and neutral to power its electronics. You need to find whether there is a neutral present at the switch that is part of the same circuit as the hots.
We can see some white wires, these may be:
a) Neutrals from the correct circuit, in which case the timer can be connected without any rewiring.
b) Neutrals from different circuits, which must not be used.
c) Not neutrals at all, white can also be a permanent hot in a switch cable, or a traveler in 3-way setup.
We might be able to work this out if you can show us the wiring behind and attached to the other switch. Also, is the light that the other switch operates, fed from the same breaker in the panel?