mods: I realize that this post wanders into off topic area but I am responding to a direct question of a new poster, who does not seem to be familiar with the rules here.
It was really interesting to find out the meaning of my surname. How would I find details about my grandparents who were born in Poland?
To start with: Get as much as possible of the vital data regarding your father and grandparents: given names, dates of birth, marriage, death. I am assuming you live in USA, so you could get some of this data from local records: books, papers, cemeteries, parishes, voting registrations, census data, etc.
For example, this webpage: Emmigration from Triple-village: Istebna, Koniaków, Jaworzynka to USA. describes life of Cieszyn Highlanders, who settled in mining towns around Sheridan, Wyoming: Dietz, Acme, Model, Carneyville (later Kleenburn), Monarch, Kooi. There were 20 Legierski people living in Sheridan County at some time. There were also some Legerskis (with slightly different spelling) around there; one list of Red Cross donors (of 10$ or less) during the WWI, contains the following Legerski names: John Legerski Kiepus, Mike Legerski, John Legerski, Paul Legerski, Joe Legerski, Mike Legerski, John Legerski - all from Kooi, and George Legerski from Acme.
Another good source of information are Ellis Islands Immigration records, publicly available. You can scan them for various legitimate variations of the surname Legierski, Legerski, Legersky. One good soul has extracted a list of all immigrants that have come to USA from the so-called "Three-village" (Trójwieś) in Cieszyn Silesia: Istebna, Koniaków, Jaworzynka - in a period of about 20 years, between 1903-01-26 and 1923-12-10. This list is available here Ellis Island immigrant list by date and ship. You can extract from there all Legierski/Legerski/Legersky records for this period. [If this list does not cover the period of your interest, then you would have to go back to the original Ellis Island records]
Here are few observations, coming from that list:
There are 10 records for Legierski, 19 for Legerski and 6 for Legersky. Of the latter surname two persons were identified as Bohemians (Czechs) from Koniakov; one from a mysterious village Kanighaw, Hungary; and two as Polish from Koniakow, Austria.
I do not know whom to blame for all those misspellings: the clerks in Antwerp or (mostly) Bremen or the immigration officials in Ellis Island. I somehow cannot believe that any German clerk would misspell Silesia as Siberia or Tilesia; and Galicia as Galicy.
Here are the name variations (mostly misspellings) you can find there:
Polish Galicja, Austrian Galitzen, English Galicia => Galicy, Galicia, Galizia
Koniaków => Kaniakow, Kanighaw (Hungary), Komakov, Komakow, Koniakan, Koniakaw, Koniakov, Koniokow , Konikow
Istebna => Fstebue, Istebna, Istebne, Istebuc, Jistebna, Jstebna, Jstebosa, Tstebna, Tstebria
Silesia => Tilesia, Siberia, Silesia
Jaworzynka => Jaworzinka, Jaworzynka, Yaworzynka
After you have clearly identified the American side of your grandparents life, you need to continue your search in Poland. The task is unfortunately not that easy, since there is no central archive yet for that area. There is some work being done on digitizing all the archives of Bielsko-Żywiec diocese to which Istebna deanery (dekanat) belongs - with its various parishes in Istebna, Koniaków and Jaworzynka. Until they finish their digitizing work all you can do at the moment is to contact specific parishes and require copies of specific baptism, marriage or death certificates. Such service is not very expensive, but it is not free. I am assuming that your grandparents were Roman Catholics. In case they were of Evengelical-Augsburg (Lutheran) faith you can browse the certificates in both standard and digital form at Tschammer's Library and Archives in Cieszyn, [biblioteka.cieszyn.org.pl].
You can find more about this subject (in Polish) here: gazetacodzienna.pl/artykul/kultura/jak-szukac-przodkow-stela-1