introduction of an essay about technology has a possitive or negative effect in our lives ..
Well... I can see others have given you good feedback as to how you should get going with this. The following suggestion by kurianjoseph is excellent;
There has been a significant advancement in the field of technology and science over past few decades. These advancement made it possible for human being to walk on moon. Although, these development offers many benefits, some people argue that technology will bring destruction upon earth. This essay will analyse the merits and demerits of technology before a reasonable conclusion can be drawn
As he suggests, you need to introduce your topic theme. kurian has done it with the first two sentences. Then he brings up the argument in the third sentence and sets up the link to flow into body paras. So, this is a good example how you should do your intro. Do it yourself and post it here and we would provide you with our comments to improve.