AFL Code writing, modification in existing TSI AFL (true strength indicator)

If you are experienced AFL coder then (only) please contact me asap. I need a simple basic code to convert existing TSI (True strength indicator) and generate buy/sell, short/cover signal based on simple criteria. Needs back testing etc. TSI AFL is available, we need to subtract TSI value from its Avg and create buy/sell signal based on that. Pl see attached TSI AFL and sample of new indicator "say Ravi" (how it will look like). This Ravi will generate buy/sell, short/cover signal based on "a""b""c""d" points marked on chart ([login to view URL]) My budge is max $50 (That's max)