I have developed two apps that should help:
Statistical Product Forecasting - this app allows you to quickly update lists, load 24 months of history, and generate a forecast at a product level. You can use this as is or modify to fit your needs.
Linear Regression Learning App - simple example on how to execute regression in anaplan
I will be releasing an improved version of Stat Forecasting in the next month or so, but the current version should fit your needs. Both of these apps can be downloaded right from apphub.com. Click on 'get app' and follow instructions.
Let me know if you have any questions,