Year	Month	Sales ($ millions)
2017	1	35030
2017	2	33372
2017	3	38022
2017	4	38373
2017	5	40139
2017	6	39409
2017	7	39197
2017	8	40617
2017	9	40746
2017	10	41117
2017	11	39586
2017	12	39446
2018	13	38623
2018	14	36777
2018	15	42048
2018	16	42509
2018	17	47449
2018	18	46946
2018	19	47391
2018	20	48233
2018	21	44985
2018	22	47742
2018	23	42639
2018	24	39026

I successfully found the trends and the index and did a regression on excel but I am struggling to find the forecast and absolute error. I feel like I am missing a step some where along the way.

Step by step guidance to find the forecast and absolute error would be helpful.