Report Writing Query

Reports Query: Hi, I am trying to runa report bto show me the candidates that have been 'Hired' by their source. The problem I have is that the most of our candidates 'source' is showing as 'Imported by Parser' rather than the actual job board etc. We do have another mandatory field so we know exactly which souce the candidate has come from. Can we either amend the existing report (but I cannot see we can slelct our own data fields) or write a new report that allows us to use which data fields we have set-up for candidates? Many thanks, for your help.