Forecast data using sim function

Hi, I have a an array with 48 values ranging from 1 to 48 obtained from a gaussian function. I want to simulate this and forecast the values for the next 12 values. Please suggest how to do this.

Would the 'sim' function work or should I use the 'forecast' function. Also,which model is preferable for 'sales' data. moving average,auto regressive or any other?

Thanks in advance.