If the pattern shows the increase is worked in two colours, it is very simple to do, just follow the steps below:
1. Using the first colour yarn work a purl stitch
2. Take yarn used to make the stitch backwards, between the two needles, as shown below, do not knock the old stitch off the needle.
3. Insert needle back into the same stitch as shown below
4. Using second colour yarn, complete this knit stitch
5. Now work across the row, starting with the third stitch on the chart, stop when you reach the last stitch on the needle.
6. Knit into the last stitch with the first colour shown on the chart, do not knock the old stitch off the needle.
7. Using the second colour knit into the back of the same stitch, this twists the stitch as you work it.
Increases can be made in the same way on purl rows, but knit the first and last stitches of the row, using whichever colour is specified in the pattern and work the second stitch of the increase as a purl stitch.