Prasenjit Purkayastha

While using the Chrome browser, type 
"how to pronounce " followed by the name of the parts of speech you want to pronounce. This will open the Google page where you can listen to the pronunciation in Indian, British and the US English. You can also test your own pronunciation by using the "Practice" option (currently it seems to be available only when US English is selected). Give it a try. 

For details of each of the parts of speech, it's already provided in the previous responses by others.

While there are multiple ways one can improve one's skill in spoken English, the first and foremost thing to do, ideally, is to find out the areas challenging one's ability to speak fluently, correctly and confidently in English. Once that is done, then the next steps become more guided, whether by self or a mentor, and the rest becomes quite easier through regular and dedicated hours of practice.

While it is comparatively challenging to achieve, yet, having a neutral accent, i.e. an accent purely derived from English phonetics works best across the English speaking populace across the world. Simply because a neutral accents is devoid of an regional imprint, and so it does not require a habitual ear to understand what is being spoken using it.

The next option is to imbibe a Midwest American accent, which is more widely and formally used in the US. It would require some decent practice to develop a habit of speaking in such an accent though.