You can make use of the Polish national employment service (Urzad Pracy). However, the national employment service only has limited job offers, so you might find it difficult to find information for appropriate vacancies there. You can find their services online at www.praca.gov.pl (information is only available in Polish).
Private employment services in Poland
You will have better chances if you look for a job in the private sector. Look at offers from recruitment agencies and agencies for temporary work. Agency services are usually free for candidates, but some may charge a fee. You normally have to fill in a form (in many cases you can now do this online) or send in your CV with an up-to-date picture. You can find job offers and further information at: www.adecco.pl, www.randstad.pl, www.praca.pl, www.pracuj.pl and www.jobpilot.pl.
Finding a job trough the internet
You can also search for jobs via the internet, try: www.jobs4.pl, www.gazetapraca.pl, www.pracaikariera.pl and www.epuls.praca.gov.pl. Note that the information on these sites is only available in Polish.
Foreign posting through your employer
Perhaps the easiest way of working in Poland is if your current employer has operations in Poland and you can get a transfer. With such a contract you normally get additional expatriation allowances, international travel insurance and possibly even a bonus for family members. Your employer will need to initiate the employment visa application process. In this case you and your family should be able to get a residence card (karta pobytu) without any difficulties.