OK....... Stay by her side, talk to her in a gentle voice, and only step in if something seems not quite right, she should mannage fine on her own.
Make sure the room is warm and that she is comfortable. You will see blood coming from her vulva before any kittens arrive, don't woory its normal.
When the kittens finally arrive, the first one will be enclosed in a bag of fluid, this should burst and the mum should lick the kitten clean and cut the umbilical cord with her teeth. If she doesn't you may have to cut it with a CLEAN scissors, but make sure you tie the cord between the kitten and the cat. It's important to do this well not to endanger your kitty's life.
A placenta appears immediately after every kitten, once this happens the mum will usually eat the placenta. If a placenta doesn't appear after every kitten then this can cause an infection inside the mother. If you are sure that a placenta is still inside of her, ring the vets and ask about this.
Once the kittens are breathing and licked clean place them next to the mothers nipples, normally it will start to suck. If it doesn't then you'll have to keep trying, as kittens need the mothers milk straight after birth.
Hopefully that helped, keep us posted on her and the kittens progress.