Welcome to df k187! Very vague questions...
merengue - your basic step is 1,2, 1,2 or quick, quick, quick...classic merengue that everyone knows is Suavamente by Elvis Crespo
salsa - Your basic step is quick, quick, slow....many songs..good Cd with nice variety to "salsa fresca - hits of the 90s)
bachata -- you step quick, quick, quick, hip raise...one bachata CD I can think of is "bachata rosa"
I could go on about the different instruments that play etc, histories etc...but then I would be here all day. I suggest you do searches, such as for "bachata" to find about bachata and build up your knowledge that way.