reflexive verb

 I think the basic meaning is when you want to say It is done, it is said etc... you can use SE... and the verb. I think you have to just learn it as the man says.

¡Muchas Gracias ferampo! 

Hello Dennis.

Well, in this case the use of "se" is impersonal, that means everyone who wants to dance "La Bamba" has to have grace (meaning coordination and "arte" as we say in Spain). The lyrycs are not talking about you/he/she, it's a general reference. 

For example, in Spain you can see some adds like this:

-"Se necesita asistenta"

-"A cleaning lady is needed"

So the translation of the sentence in the song could be (sorry for the mistakes in advance..):  "For dancing  La Bamba, a little grace is needed"

The bad side is... in Spanish it doesn't work always that way. This is something you'll learn over time.

"Se" is one of the worst parts of learning Spanish, in fact there are many spaniards that don't master this part of the grammar and misspronounce or make many mistakes, so don't be too worried about understanding every single rule of the grammar because it'll be impossible. 

I hope this is going to help you a little because this issue is complicated to explain and to understand, maybe some friend here can be more accurate.

If you need more help only whistle, see you.