Double front post and double back post stitch

[mdkb904]

I’m using a chart for a blanket that I’m working on so the white boxes on the chart are single crochet and then the blue boxes are double front post for odd row and double back post for the even rows so how do I work double front post and double back post on a single crochet row from Melissa 

[bgs]

https://www.mooglyblog.com/post-stitches-into-single-crochet/