would you be able to suggest a good website for me to answer this question

granite is intrusive , felsic rock, which may be produced by partial melting or fractional crystallization, Explain how these processes produce felsic magmas from more mafic parent magmas (200 words)

would you be able to tell me how i should tackle this please

These two sites may be of some help.

http://www.khulsey.com/jewelry/rock_cycle_igneous.html

http://jersey.uoregon.edu/~mstrick/geology/Geo_Lectures/Volcanoes.html

Since this is not my area of expertise, I searched Google under the key words "granite" to get these possible sources:

http://en.wikipedia.org/wiki/Granite
http://www.fi.edu/fellows/fellow1/oct98/expert/granite.htm
http://volcano.und.edu/vwdocs/vwlessons/lessons/Rocks/Rocks10.html

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

I hope this helps. Thanks for asking.

Also on the uoregon site is AskGeoMan, which has answers to many geology questions.
Easy to find by typing AskGeoMan into Google.