this is not a beginner friendly tutorial but if you already know what you’re not a beginner and already know how to crochet this is a great tutorial! I found it very informative and not to much talking in between directions.
In order to get the back a little wider what do you do to increase is it by adding more double crochet into each chain at the back? I just recently started to do Bikini I use to specialized in ladies church tom and earrings.
You can start increasing on the very first row in the back section - if you wanted it even wider you could try increasing into the first 2 stitches on each end instead of each 1