The Salsa Dancing Event is a 7 day Limited Time event which is unlock after you complete A Dance To Remember.
Basically you just need a juke box and a decent sized area to Dance. You can get multiple couples involved to speed things up. You need to collect 12 trophies before time runs out. At the time of writing there are two dance options one takes an hour and a half and the other a lot longer.
On successful completion of this task you gain access to the fantastic Latin Villa template plus gain access to the Break Dancing Hobby.