Hello. I’m new at this. Knitting the sleeve of a cardigan and not comprehending the pattern, Dec 1 st at each end of every alt row ? Is that at the end of every second row? Yes I know me not the pattern 
What pattern are you working? Post a link if you can. Usually every alt row means every other row. If we name the first decrease row 1, you’ll decrease one stitch at the beginning and end of rows 1, 3, 5, etc. for the specified number of decreases/rows.
Unless the pattern states differently, I make my decreases a couple of stitches from the edge for a smoother line on the selvage.
Thank you so much, that is just what I wanted to hear. I will have to pull out about 4 inches, so happy i found this site, I would have been very upset if I got to the end and then found out I was wrong oxox.