The only way everyone knows what everyone else is talking about with any degree of certainty is with verb tenses. Verb tenses are absolutely necessary to fluency in English.
Grammar it is, is one of the most difficult things to get consistently right. Every grammarian will tell you of their utter surprise and dismay concerning the lack of grammatical acumen in even those who hold degrees from top-ranking universities.
It's a lifelong forge, but the rewards are worth the effort. English verb tenses help organize your thoughts and your writing. Clarity in spoken and written communication permits you entrance to a world where ideas flourish. If being part of the intellectual community is important to you, English verb tenses need to be important to you, too.
Simple present is used when the action being described is habitual or constant. It's very, um, simple because all you have to do is use the first form of the verb you want.
Notice how singular third person verbs change; each gets an "s."
The simple past is pretty easy, too. It describes a single event in the past without reference to any other past action. It's really important to know that the simple past is only for singular events because there are other English verb tenses to handle more complex situations. The simple past uses verbs' second forms. Piece of cake, right? Not so fast, turbo. This is the first tense in which the dreaded irregular verb comes into play.
Notice that the time periods and actions being talked about in the examples are all unquestionably finished and firmly in the past. Also notice that not all the verbs end in "-ed." Some of them are irregular, and it's up to you to remember which ones are which.
Irregular verbs are one of the major catches in English, but if you work hard at them, you'll get them straight in no time. The most important ones to know are "to have," "to be," "to go" and "to do" because they all work as helping verbs in other tenses.
The simple future is super simple because it only describes a single event that has yet to occur. If you've been paying attention, you'll notice that the simple future is just like the other simple tenses. If you understand the simple past and present, this one will be a breeze. The only tricky thing is that it has a helping verb.
When to use the helping verb, "will," is sometimes up to you and how you want to speak. A good rule of thumb is to use "will" when the future event is a promise or a prediction (almost always). Don't use the helping verb when you're saying something will happen irrespective to anything else.
Examples using "will":
Notice how similar the simple future looks to the simple present when you don't use the helping verb "will." When you're talking about schedules and appointments, you can usually safely drop the helping verb, but be careful.