I really want to congratulate you - you are doing brilliantly getting organised for this coming foal, especially considering how this event has been rather sprung on you with very little warning!
In the case of a possible red bag, I would put a quick call into your vet as soon as anything red instead of white is STARTING to show, then get busy yourself carefully cutting the bag and getting the foal out. A lot of red bag deliveries are straightforward (foal is following normally) but in some the foal can be mis-presented, so the fast attendance of a vet is important.
Here we never just sit back and watch our mares give birth, we always try to assist. Once we can see the little nose appearing on top of the legs we move in to offer help, grasping the foals legs by the cannon bones (not the hooves) and GENTLY keeping a downward pressure with each of the mare's contractions - no pulling! As a maiden mare she will obviously be 'tight' and you may wonder if the foal will ever get through, but take it slowly and all will be well.
Once the foal is out, the most important thing to do is to immediately clear the birth bag from its head (if it has not already broken) so the foal can breathe. Time to take a big breath yourself LOL!! Leave the foal where it is, still attached by the cord to the mare, possibly with the back feet still very close or even just inside the mare - do not pull the foal away as this is the time when extra and important blood is passing from the mare to the foal via the cord, plus your girl will be taking a breather herself after all the effort.
Cords usually break naturally after the end of the blood flow period and when the foal starts to struggle to it's feet. I have only found it necessary to cut a cord when the foal is trying to get up and the cord doesn't break - make sure you have some scissors safely right to hand in case this should happen - you wont have time to go and find them and it is very important that the foal doesn't start to pull the afterbirth away from the mare. Never pull on the afterbirth, it will come away naturally on its own - this can take several hours!
It can help to give the foal a little rub down while it is lying there, (and dont forget to peek between its back legs/under its tail to check for the sex!!) but basically once baby is trying to get up and the cord has broken, now is the time to remove yourself from the stall and leave Momma and baby to find each other. Keep a good watch from outside the stall - you need to see baby safely on its feet, Momma up on her feet and to watch her reaction to the foal - first foalers can sometimes be a bit amazed to suddenly find this strange little being in their stalls!
Now you will get many different 'thoughts' on what to do next, but I am very strongly for the idea to leave well alone! This is an extremely important time for a foal to bond with its mother - foals do not have good eyesight and learn to bond with their dams by scent/smell, too many humans in a stall at this time (people helping the foal to its feet or even a vet manhandling a new foal to check it over when not necessary etc etc) can really confuse a baby and often means that it starts to follow/look for humans in those first few hours instead of knowling the scent of its dam. It can also cause a lot of stress to the mare who can get very protective of her baby, so leave well alone - this is when you want the endless cuppas while you keep watch to see that all is well and that the foal is progressing normally plus that your girl is happy to accept her new baby.
Your mare will have done piles of 'sloppy/loose' droppings at the onset of her labour - natures way of clearing out her system. About an hour after she foals give her a small wet feed of her usual food and follow this up with several small wet feeds for the next 12 hours as her system requires moisture going through it to 'kick' start it again. If all is well she can have a supply of soft hay to munch on after that first wet feed. I suggest that you remove her water bucket as soon as labour starts and replace it once the foal is born, but this time tie it up within reach of the mare but out of the foal's reach - many babies have drowned by falling into a water bucket during their first attempts to get to their feet!
The only other thing I will add is this - maiden mares do normally take longer to foal than mares that have had several babies, but if your mare has been having contractions for longer than 15 minutes with no sign of the coming baby - call your vet as help may be required.
Good luck, our fingers are crossed for you, and remember at least 90% of the time everything will work out fine, it just pays to be alert and ready to help and to share in the wonderful moment of birth.
