Task to design a performance appraisal system with implementation - how to do it?

I have been recently step into the HR job, i have given a task to design a performance appraisal system with implementation can anyone help me plz that how to do it?

Dear Tosh, Performance management system is a Science, I wonder how as a fresher (i suppose) you could do it.
Anyways first go through the theories and concept of Performance measurement and people development strategies organizations adapt. that may include career planing and development, succession planing and reward and recognition as Performance management is linked with these HR systems as well.