Are there opportunities to explain its someone you step by step how should we connect with the ECU program which, with What kind of cable ?

Good evening from Poland, my guess is you need an interface first, that will depend on vehicle model you`ll work with. The most used is Galletto2 now (at least in Europe i suppose) but there are million of others. Better if you have an original- not cloned hardware, that makes errors possibility lower. Make sure it`ll cover your ECU and get to work!
Once you get an interface, you`ll need get the dump and process it properly with an appropriate program, checksum it and flash your ecu back with that mod file.

AAAAH!!! and one more: choosing your hardware be sure about what`s really your target: just fun with maps and changing turbo sooner as you thought (lol) or professional reprogramming not only for power, ex. EGR, DPF, IMMO and many other - i mean not all hardware reads dumps entirely or in a proper way , mind it anyway.
Thats just a little bit of chiptunning general concept.