My wife returned to Poland after she overstayed her visa more than a year. What are the necessary steps for my wife to return to the US ASAP ?

The answer depends upon whether you started the immigration process and your immigration status. There is no overnight fix. Your wife will need to wait until a Form I-130 is approved and a visa is available at which time she will apply for an immigrant visa through consular processing. At the visa interview, she will be refused due to her unlawful presence. She will be instructed to file a waiver based upon extreme hardship to you if she is denied admission. Once the waiver is approved, your wife's visa will be issued and she can return to the United States. Your wife should not attempt to enter without an approved immigrant visa as it could irreparably harm her ability to obtain a green card.