cast on is never a row.
one row is a needle form end to end
knit row 1 with color A
knit row 2 with color A
(that makes a color block in garder stitch)
knit row 3 with color B
purl row 4 with color B
(carry your yarn up the side. tying in the ends would be hell and make the structure more apt to end in problems after a while (knot coming undone and so on)
the blanket will have a right side and a wrong side alright, though.
Where you do the purl row (row 4) shows the wrong side. from the right side the blanket will have a stochinette part for color B. the wrong side will alter between garder stitch and purl bumps.
the altering is on purpose for the right side, since it creates something like a rib pattern (up and down)
don't worry: the look of the blanket from a little distance will be almost the same for both sides. From closer up you can see a good and another side
Enjoy your project!