LGBT stands for Lesbian, Gay, Transgender, Bisexual, and Queer. Here are the definitions and flags for them:
Lesbian means a woman attracted to women. Gay is a man or woman attracted to the same sex WikiPedia says: Transgender people have a gender identity or gender expression that differs from the sex that they were assigned at birth. Bisexual means attracted to males and females.
Queer can mean not straight or not cisgender I could not find a few flags but these i could find:
Lesbian flag
Bisexual flag