Full length mala necklaces are composed of 108 beads and a guru or finishing bead that unites the two sides, ending in knot work, a tassel or smaller bead grouping. In some mala necklaces, beads of different size or texture may be placed at regular intervals (generally in multiples of 9) to aid the wearer in their mantra practice. Rainework mala necklaces often contain these marker beads every 27th counting bead, and as they function as a marker they do not count in the overall total of 108.
Malas may also be created in smaller sizes and can be created with 18, 27, or 54 counting beads.
How you hold your mala during meditation is a matter of what works for you, though there are certain traditions in specific faiths that you may want to read up on if you are new to the practice. I personally hold my mala in my left hand and loop it easily over my right palm, sliding the beads between my thumb and middle finger as I count.
You may choose to repeat a word each bead or recite a mantra. You may set an intention at the first bead and repeat it for each subsequent bead. Your counting may be internal or it may be out loud. You may chose to breathe while moving through the beads: one full inhale and one full exhale per bead.
Finding a practice that is meaningful to you may take time and that's just fine. There is no one keeping score; you may try several different forms of meditation before finding your own personal practice or you may love the first you try. Be patient. Remember that just as what we need to stay balanced and grounded may change, so may our practice change. What resonates one day may not the next. As you continue to explore you will begin to build an internal library to call upon. Enjoy the journey of discovery.