Present Continuous Tense: is/am/are

1. For an action going on at the time of speaking:
I am typing this mail(now).

2. For a temporary action which may not be actually happening at the time of speaking:
I am reading "Psychology of Aggression".

3. An action that has already been arranged to take place in near future:

I am going to reply to this post.

The following verbs are normally not used in Continious form:

a. Verb of perception: see, hear, smell etc.
b. verb of appearing: appear, look, seem
c. verb of emotion: want wish desire etc.
d. verb of thinking: think, suppose, believe, agree etc..

Present Perfect: has/have:

1. To indicate completed activities in near future:
He has just gone out
2. To describe past actions when we think of more of their effects:
I have cut my finger( and it is bleeding now)

3. To denote an action begining at some time in past and still continuing:

I have known him for long time.

hope it helps..