How to forecast a multi step ahead time series?

Hello all,

I'm doing a new project on MATLAB. I got stuck in a step where I have to forecast a multi step ahead time series.

Any code snippet will be very helpful for me to proceed. Kindly help.

Problem :

I have a time series data of 578 points and I need to forcast next 144 points which are unknown to me. These 144 points will be multi step ahead forecast points.

The problem can be seen as I have 80 percent data with me and rest unknown 20 percent I need to predict. (Any relevant approach is great for me)

Thanks in advanced.