You start with a fold. Yes a fold. Create the fold where you would like the tuck to be.
Then sew along the fold. The further from the folded edge the larger the tuck. Make another fold and sew another line.
Then you have created nice little tucks of fabric. Iron them to the side you wish for them to lay and you can stitch along the top to hold them into place. Create as many and you like and space them as close or as far as you like.
Create pin tucks by sewing close to the edge.
Adding tucks to any garment is easy to do. You can add extra room to the pattern and sew them in after you cut it out. Or you can sew the tucks into the fabric and then line your pattern up over the tucks the way you want them to be on the garment. Like I did for this pocket.
A nice little row of pin tucks right where you want them.
So have your try at some tucks they will easily spice up any garment.