Help with forecasting

The problem i have is i am current supplied with a forecast that I don't think is very accurate, i have tried using the functions within excel but i cant seem to make it much better either.

i was wondering if anybody has any existing sales forecast models or any clever ways to predict daily forecasts based on previous data.

here is some data if it helps https://www.dropbox.com/s/8gnmzv8wen...pped.xlsx?dl=0

any help would be greatly appreciated.