Grammar isn't my favorite part of teaching Spanish, but it's important to understand the structures and "rules" of any language you're learning.
I highly recommend the following sites:
StudySpanish (great grammar explanations & other resources) WordReference (a language dictionary and forum with many additional features) ¡Conjuguemos! (an online game for practicing verb conjugations)
I've also compiled a few resources here that I've created over the years...
