I want to know financial modelling particularly FCFF model for valuation of companies?

Answer 1

Take a look here:

http://pages.stern.nyu.edu/~ADAMODAR/New_Home_Page/lectures/val.html

The whole ADAMODAR site is interesting if you are interested in stock valuation and related problems (like how to gather the information and make the guestimates)

Answer 2

Financial modeling is an extremely broad topic which pertains to quantitative analysis. The Free Cash Flow model is used to forecast the projected operating cash flow (less capital expenditures and incremental working capital), which is then discounted (usually at an appropriate Weighted Average Cost of Capital). The present value is how much you should be willing to pay for a particular investment/acquisition target.