This is how to increase a stitch; however, this makes your work larger. You can also use with double or single or treble stitch as well. I use double crochet a lot in my hats. This is also written and visual from Crocheting for dummies at http://www.dummies.com/crafts/crocheting/stitches/increase-double-crochet-in-the-middle-or-end-of-a-row/
Note from website about increasing: You can increase (abbreviated inc) double-crochet by adding a stitch at the middle or end of the row. When increasing double crochet, always count your stitches to make sure you have the correct number on your work. If you’re working from a pattern, it’ll tell you where to place your extra stitches, so no guesswork is needed.
Work across your row until you get to the designated increase stitch or the last stitch of the row.
Crochet the stitches that your pattern calls for. (When increasing stitches, always count your stitches to ensure you have the correct number on your work.)
Work 2 stitches into the designated stitch from the previous row.
By working 2 stitches into 1 from the previous row, you are increasing your current row by 1 stitch. If you want to increase your current row by 2 stitches at once, then work 3 stitches into 1 from the previous row.
Take a look at the symbol for a double crochet increase in the visual section of this blog.
Share your ideas on this or anything here on the blog either here or e-mail me at firstname.lastname@example.org. I look forward to hearing from you