Knitting machines can produce stitches very quickly but they cannot produce a wide range of stitches. Extra attachments are needed to produce purl stitches using a knitting machine. It is possible to produce entire sheets of purl stitches, such as for the garter stitch as well as ribs where you have purl and knit stitches alternating. If your knitting pattern requires a lot of purl stitches placed at different intervals throughout the piece, then hand knitting may be the best option.
Install the ribber bed perpendicular to the main knitting bed. This is used to produce alternating knit and purl stitches. The knit stitches are knit on the main bed and the purl stitches in the second ribber bed. The actual installation instructions depend on the knitting machine being used.
Remove the main knitting bed and install a garter bed if you just want to produce purl stitches with no alternating knit stitches.
Load the yarn onto the machine and start knitting. Be aware that the garter carriage can only be used with one colour yarn while the ribber carriage can be used with different colours of yarn when purling.