In which way can I use operational amplifiers to amplify XLR signals?
Can I simply connect 3 and 2 to my operational amplifier and than take
  the output (4) from my operational amplifier, combine it with the GND
  (1) and connect it to a speaker?


No that won't work as well as you'd expect it to. Firstly an op-amp is not a power amp (OK some are but these are very much more specialist devices) and you might only be able to get 40mA out and into an 8 ohm speaker that's about 12 milliwatts - about 1/4 the volume of a 1 watt amplifier (which of course you can get from the usual semiconductor sources).

Secondly, an op-amp is more akin to a mathematical device whose precise behaviour is defined by a set of resistors placed around it. If you fed -Vin and +Vin from your XLR signal it just wouldn't work and you'd either here nothing coming out or, it would sound a mess of distortion.

As for circuit ideas for a pre-amp you'd need to define how big and how small the inputs are going to be (millivolt levels), what input impedance you are looking for (microphones need less than guitars for instance and keyboards barely care providing the input impedance is over 100 ohms). Output level required and the output impedance required (usually less than 100 ohms is fine). What power supplies you'd expect it to operate from and probably a few other things like noise levels and bandwidth.

Or, just tell us what you are trying to achieve in terms of inputs and outputs and maybe google a bit for ideas.