extracting sales order from R/3 to BW

hi frends,

it is very urgent where i have to extract the data from r/3 to bw and create a report. my tl has give a doc which is not of technical bw doc but it is some functional doc where sd already created a report on that. i want to do the same report in bw.

how to start with from r/3? whether already setup tables r filled for this sales order datasource i need to do it?

or else i should ask some body to fill that?

how to start with out any bw technical doc like which r the datasources i have to use and regarding business content what r the things i have to activate.

pls help me how to approach. and what r the prerequisites i have to ask them?

boss it is really urgent..

help will be highly appreciated.

thanks & regards\

rakesh