What are Judaism's prayer services?
That is not easy to answer. Some prayers (Pesukai deZimrah and
Birchos Kerias Shema) are said sitting, and some (Baruch She'amar,
Shemoneh Esrei and others) are said standing. Some are recited only
by one person (Torah-reading, Chazras HaShatz), some are said by a
portion of the people (Birkas Kohanim, Yizkor), and some are said
by everyone. Some are said aloud (Shema, Amen, Vezos HaTorah), some
are said quietly (Baruch Shem Kevod, Shemonah Esrei) and some are
sung (Lecha Dodi, El Adon). Some require a quorum (Kaddish,
Barechu). Some are said every day, some weekly, some on Sheni
VeChamishi, and some on various occasions.
Browsing through an annotated siddur (such as the Birnbaum
prayerbook) should help. Generally, other people in the shul
(synagogue) will be gracious and helpful to a newcomer.