@Muhammad_Rab_Nawaz_B Alexa is a tool which can measure site rank in search engine by using various factors. If you already placed Alexa code on your site so Alexa can give best optimum analyzed site metrics. Which also can help you to improve your site rank in search engine.
At this time we have no video guide on Alexa but as soon as possible we will make any video tutorial on it and will must embed this video on this topic for your convenience.
You also can browse many written topics on Alexa on this forum by using header search option.
Hope that will help you!