For demonstration purposes I am going to show the basics to make a small square and you can adjust for a larger piece later...
This is in U.S. crochet terms... I am using 4ply worsted weight yarn....what I call regular old basic everyday yarn.... and for this I used a ( I ) hook...
So. Chain 26 then hdc in the third chain from the end.
this method of color changes moves you into a new color evenly
ch 1 and turn
In order to have a nice neat border on both sides....one bobble row starts and ends with 5 sc and the next bobble row starts and ends with 3 sc.
you can start your first bobble row with either the 5 row or the 3 row just make sure your next bobble row is the opposite.
I do hdc as my first row because it is firm but a little bigger that sc...you can do double crochet and use double crochet between the bobble rows....but your bobble rows must be sc sc sc bobble sc sc sc bobble to the last 5 or 3 which ever you chose as your first bobble row.
well ! there you are!!!! I hope it is clear....let me know I am happy to answer any questions!!!