Required C# developer for coding Ninja Trader 8 Indicator

I need to edit a pre-built Simple Moving Average (SMA) indicator in NinjaTrader 8 (NT8). In the SMA indicator, when I set the period to 1, it shows the close price of the previous candle. Now, I want to add a new option in the parameters. For example, if I set it to 2, it should give the close price of the candle before the previous one (i.e., previous candle - 1).

Note: I need to make these edits in the existing code, instead of using the close price, I will replace it with another value in the Market Analyzer."