One of the main points in your essay is that rich and developing countries are intertwined and what happens in one country has an effect on others. I thought this was an interesting way to approach the topic.

Thesis Sentence

However, I think your essay needs a clearer introduction and particularly a thesis sentence to tell readers what you are going to do. 

It's not quite clear from your opening sentences if you are going to talk about the environment, health, international relations, financial assistance, sharing of human expertise or other forms of interaction and cooperation.

As a result, the essay wanders a little – it needs to be more focused on one or other areas.

I interpreted the question (there is an example essay here) to mean financial help or aid. However, IELTS is fairly generous with regard to being on topic: you can interpret the topic quite loosely and approach it in many ways.

Comma Splices and Run-Ons

Watch for comma splices (sentences which should be separate but are joined with commas) and run-on sentences (sentences which should be separate but are just joined together any old how!).

Your first sentence has examples of both:

Alia wrote:

All of us are in the same boat, what has been happend here, should affect others there, our planet act as a small village all of us live in it. 

This could be rewritten as:

All of us are in the same boat. What happens here can affect others there. Our planet is a global village. Why can't we all just get along?

I really like your last point:

developing countries are in need to lend them a hand, not only for themselves, but in the same time for  ourselves as well.

 With a little editing, this could read as:

Giving developing countries a hand will not just help them, but us as well.

In case of my point of view, poor people have no enough awareness towards the envirnoment or their behaviour against it, you may find some of them reject the wastes in any where, without any consideration to the consequences of such a disposal  on the surrounding environment.

As we know, due to poverty, most of the poor people may be uneducated, so that you will see lower degree of hygine  and healthcare measurements, that will leads to some epidemic diseases as Poliomyelitis, which couses paralysis to the children if they have not been vaccinated before one year of  birth. And  Malaria which couses  death to so many of  poor people in africa .

All this conditions, affect not only the country in which it occur but, in the same time all other countries . More over, if we helped them we may eradicate  diseases like this from the world. As example Poliomyelitis, where the  WHO can lower its ratio to a much extent, it has approxemately disappeared in Egypt .

For instance, we can not speak about our planet's climat or environment or global worming or any of this aspects,  which the recent scientific researchs discuss now, we can not discuss this aspects with some uneducated, poor, and sick person who suffers poor feedig . He will not apply all this measures which needs awareness and high lifestyle .

 Second, We should help them for the benifets of all the humanbeing where, what happened in the far east will affect in the  far west. that is our fate .

From another point of view, some opponents say that, we can not help them for ever, they should depend on themselves, work and develop their countries through their efforts not depending on our resources, they are lazy do not give their work the required effort and devoted time to allow their country to be like the well developed,  first world countries .

To sum up, developing countries are in need to lend them a hand, not only for themselves, but in the same time for  ourselves as well. Otherwise all of us will suffer what is  still unknown about our planet climate and global warming .