I am dating a Salvadoran man?

Lately he has been mentioning marriage which I am very excited and happy about but after meeting his family I am extremely afraid I won't fit in. His father is from El Salvador and his mother is from Mexico City. Having lived in a border town my entire life I am familiar with customs, suspicious and other things that are Mexican but I have no idea about the Salvadoran culture! I am of Irish heritage and it is very important to me just as much as the Salvadoran culture is to my boyfriend. What would be good reference material to learn about the Salvadoran culture? His family is very close knit and seem to be reluctant to share a lot with me :( What could I do to integrate myself into his family better?