As we grow up, we’re constantly having our grammar corrected by our parents and teachers until the rules become 
completely ingrained. It’s understandable then that when we start to learn another language, we try to apply the rules we already know to it. This doesn’t work though, as we frequently (but patiently!) have to explain to students.
With Indo-European roots, English and Spanish grammar has similarities in places, but there are also significant differences. One of the first things you have to come to grips with as a beginner is gender. As English doesn’t assign a gender to inanimate things, this is often a source of confusion early on for learners. Agreement – changing adjectives to match the nouns they describe – is still more difficult, especially in the early days when just one form can be a struggle to recall. Word order differs in many cases too. Taking once again the simple example of a noun and an adjective, the phrase “the tall man” would translate as “el hombre alto”; as you see, the adjective comes after the noun, whereas it is the opposite in English.
Verb conjugations and word endings can also be challenging for English speakers who have not been exposed to other languages, but these basic examples illustrate the danger of trying to apply your native grammar rules to a foreign language. Difficult though it can be at times, the best approach is simply to absorb and accept the rules of Spanish and forget about trying to make sense of them in the framework of English grammar. Don’t feel daunted though; the rules are not complex – simply different to English – and your native Spanish tutor will be there to help you every step of the way.