Present Simple Tense

(also called the simple present tense)

The verb 'be' is different from the other verbs in this tense. Let's look at 'be' first:

Here's the positive form (positive means a normal sentence, not a negative or a question. This is sometimes called 'affirmative')

Positive	Positive Short Form
I am	I'm
you are	you're
he is	he's
she is	she's
it is	it's
we are	we're
they are	they're

Next, here's the negative. It's very easy. You only add 'not'.

Negative	Negative short form
I am not	I'm not
you are not	you aren't
he is not	he isn't
she is not	she isn't
it is not	it isn't
we are not	we aren't
they are not	they aren't

And finally let's talk about the question form of the present simple with 'be'.

Firstly, here's the 'yes / no' question form:

Yes / No Questions

am I ?

are you ?

is he ?

is she ?

is it ?

are we ?

are they ?

If you'd like to make a 'wh' question, you just put the question word at the front:

Wh Questions
where	am I ?
what	are you ?
why	is he ?
who	is she ?
when	are we ?
how	are they ?

Present simple tense with other verbs

With all other verbs, we make the present simple in the same way.

The positive is really easy. It's just the verb with an extra 's' if the subject is 'he', 'she', or 'it'. Let's take the verb 'play' as an example:

Positive (of 'play')

I play

you play

he plays

she plays

it plays

we play

they play

• Don't forget the 's'! Even really advanced students do this!
• For a few verbs, there is a spelling change before the 's'. For example,'study' becomes 'studies'. 
.
• There are also few verbs which are irregular in the present simple:
  1. 'have' becomes 'has'
  2. 'do' becomes 'does'
  3. 'go' becomes 'goes'

To make the negative form, you need to use 'do not' (don't) or ' does not' (doesn't).

Negative (of 'play')
I do not play	I don't play
you do not play	you don't play
he does not play	he doesn't play
she does not play	she doesn't play
it does not play	it doesn't play
we do not play	we don't play
they do not play	they don't play

How about the question form of the present simple tense?

We use 'do' or 'does' before the subject to make the 'yes / no' question:

Yes / No questions

do I play ?

do you play ?

does he play ?

does she play ?

does it play ?

do we play ?

do they play ?

Just like with 'be', if you'd like to make a 'wh' question, you just put the question word at the front:

Wh Questions
where	do I play ?
what	do you play ?
why	does he play ?
who	does she play ?
when	do we play ?
how	do they play ?

When Should I Use The Present Simple Tense?

1: First, we use the Present Simple when something is generally true:

• The sun rises in the east.
• People need food.
• It snows in winter.
• The sky isn't green.
• Water boils at 100°C.
• Plants die without water.
• Two and two make four.

2: Secondly, we need to use this tense for a situation that we think is more or less permanent (see the present continuous for a temporary situation - one which we think won't last long):

• Where do you live?
• She works in a bank.
• They love coffee.
• She has three children.
• I am married.
• I don't like mushrooms.

3: The next use is for habits or things that we do regularly. We often use adverbs of frequency in this case (also see the present continuous for new, temporary or annoying habits):

• Do you smoke?
• I play tennis every Tuesday.
• We often go to the cinema.
• She gets up at seven o'clock every day.
• At the weekend, we usually go to the market.
• How often do you study English?
• I don't travel very often.

4: Four, we use the Simple Present to talk about what happens in books, plays, or films:

• The hero dies at the end of the film.
• A young woman travels through Europe, where she meets different people, and finally falls in love.
• In this book, an army invades Britain.
• The main character is very pretty and works in a bookshop.

5: We use it in the first and the zero conditional:

6: Strangely, we can use this tense to talk about the future. When you are discussing a timetable or a fixed plan, you can use this tense. Usually, the timetable is fixed by an organisation, not by us:

• School begins at nine tomorrow.
• Our train leaves at eleven.
• What time does the film start?
• The plane doesn't arrive at seven, it arrives at seven thirty.
• When does the class finish?

7: We also use it to talk about the future after words like ' 'when', 'until', 'after', 'before' and 'as soon as' in a future sentence:

• I will call you when I have time. (Not: 'will have')
• I won't go out until it stops raining.
• She'll come as soon as her babysitter arrives.
• I'm going to make dinner after I watch the news.
• I'll give you the book before you go.

8: We need to use this simple tense with some special verbs which we don't use in continuous tenses (stative verbs). 

• This soup tastes great.
• You look fabulous.
• I think she is very pretty.
• I am cold.
• I promise I will help you.

Source : http://www.perfect-english-grammar.com/verb-tenses.html