So is Spanish your native language? You said you and Husband only learned English.... So is Spanish your 1st language?
If so, then simply speak to your child in your language.
My kids, are both multilingual.
Kids, learn foreign languages well.
Better than adults.
From birth, my Husband spoke to them in his native language and I spoke to them in English.
My kids are now 8 and 5 years old.
They are, multilingual, can speak and read in both languages.
At school they also learn: Japanese, Hawaiian, and Mandarin. They are adept at it. And learn other languages well. And my kids also learn Spanish from Dora/Diego. Yes. They KNOW Spanish quiet well, from these shows.
Learning other languages, in kids, actually develops more synapses in the brain. And they learn it, better, than single language households.
The earlier you start, the better.
Just in the child's environment. Not only via formal lessons.
But, BOTH parents, have to speak it, daily.
Not using both languages in the same sentence, otherwise the child will learn incorrect grammar/sentence structure.
Are you or your Husband, bi-lingual?
If so, then use your languages with your child.
It is in the everyday exposure, that a child learns best.
IF you and your Husband do not know the language, then your child will only be learning it from a Tutor. And his everyday environment will not be exposing him to that language.
Because... becoming adept at learning another language, means... putting it to use, DAILY, in conversations. With their parent. Too. Not just one or twice a week with a Tutor. And being exposed to the language, in other ways. Via other kids, media, reading it, speaking it, etc.
ALSO, join culture clubs in your area. That is how, a child can learn other languages too. Anyone can join. Even you/Hubby with your child.