How to create data for a smooth curve

[Snarf]

I am trying to create a forecast for some data.
I have dates and quantity. When I plot it the graph is choppy. I can add a
trendline.

Is there someway for me to add the more important values, min, max a few
near the max, then get the values in between which would result in a smooth
curve?

 

[Bernard Liengme]

Try using a moving average trendline
You cannot arbitrarily add/remove data and expect the trendline to
accurately reflect the trend in the original data
best wishes