Hello Nick and thanks for this essay

Introduction

Your introduction could be much more specific. The first sentence doesn't really add that much to your essay, and could be left out. What is missing is some specific examples of the negative effects of using social networks or the internet.

This sentence could be used in a million essays.

In this essay, I will look at some direct effects and some adverse effects.

Try to avoid sentences like this. Instead, make them specific to the essay. For example

In this essay, I will look at how social networks and other online communication bring people together, and I will argue for moderation in the amount of time we spend online.

Word choice/Usage

Effects is neither positive or negative.

On the other hand, the Internet causes numerous effects to people.

You need to use the word "problem" or "negative effects"

On the other hand, the Internet can have negative effects on users.

In my opinion, although online is useful and absorbing, it is actually changing some invisible problems between you and me.

In my opinion, although being online is useful and absorbing, it is actually leading to/contributing to/responsible for/causing some invisible problems between people.

You have a mix of excellent and not-so-excellent word choice in this sentence:

In some cases, once people start to exchange ideas and feelings with their imaged friends, some friends in the cyberspace, they are unconsciously building an inner wall of isolation so that people are getting unfriendly and mean.

Here's a slightly edited version:

In some cases, once people start to exchange ideas and feelings with friends in cyberspace, they are unconsciously building an inner wall of isolation that damages their interactions with friends and family in the real world.

This sentence is not very clear. A simpler word than 'indubitable' would make it easier. Always go for the simpler word.

Personally, if those problems that I have stated above can be ruled or limited by the government then people are Indubitable to sue the Internet as much as they can.

If these problems can be reduced by the government, then I feel people are welcome to use the Internet as much as they want.

However, how would the government stop people from cutting off their real friends or from forming relationships online?

It is indispensable that people can use the Internet to contact that is the way that we can locate our friendship and connect with family wherever we are.

This is a run-on sentence  - it should be in two parts. Let's remove the word "indispensable." In fact, let's try to remove all  unneccessay introductory phrases:

People can use the Internet to find friends and connect with family.

• When people study abroad away from hometown, the Internet is always to use. ==> When people study away from their hometown, the Internet is always available.

Prepositions/Articles/Other grammmar points

• It is easy that we can connect with friends ==> It is easy to connect with friends
• For instance, to society, it is true that students are too addicted to computer when they live alone.
  For instance, many students become addicted to the computer when they live alone.
• Furthermore, to individuals, using website to connect can create a sense of alienation from individual around them.
  Furthermore, for individuals, using websites to connect to people can create a sense of alienation from individuals around them.

Overall, Nick, use simple words, make sure every sentence is specific to the essay topic, and watch some prepositions!