[Gretl-users] Forecasting Questions (newbie)

Hi, I'm sorry the following questions are going to be really basic but I've got to start somewhere... I have a time series data (temperature against time for example) and I need to predict what the temperature is going to be in the future. Is this the sort of thing that Gretl will do for me? I've had a play with Gretl and I've managed to get it to give me a couple of graphs and I've even managed to perrform a forecast run but the forecasts I'm getting are always straight lines when I would have expected something that looks like the data I have. I think what I need to learn about is statistics in general and regression analysis in particular but I'm not a mathematician / statistician so I don't know if that is correct (I'm a chemist turned programmer). I'm willing to learn what I need to know but right now I a bit stuck just figuring out what it is I should learn. Many thanks for any pointers, Graham Smith