To do this you need to create a query that sorts your data by the Month and the Year. I generally add 2 fields (TheMonth and TheYear) using the Format() function EG TheYear:Format([Date],"yyyy").
Now you have to decide on mess or clarity (HINT - CLARITY
It comes down to the number of data points. Say you have 4 products over 2 years. That is 96 data points. If you produce a single chart with all 4 products on it you would have 16 series which is messy. The better option is 1 graph per product. So create a report based on your query (so you have a Parent/Child scenario). Create your chart using Sales, Month and Year. Axis is TheMonth and Series is TheYear.
Have a look at the attached