I find it hard to believe you can't find any info on salsa on the web.....it may be hard finding websites that are in english.
The difference between most of the Brazillian and Cuban song forms takes place in the percussion section, nothing differently harmonically. To get a good understanding of this music study the "clave' rhythm and its different variations, and how to comp chords to this rhythm. Also learning how to play piano montunas on guitar will make you a favorite among percussion players.
You may want to look into studying the music of Spain, this is the roots of salsa and is a little more guitar oriented.