Okayy,
If you go into natural labour:
So first you'll start to feel contractions, they're likely to be 10 mins apart at the very beginning, maybe less or maybe more. They'll be bareable at first. For mine, I got woken by contractions at 8am. They kept happening so I started timing them and wrote them down. When they got to about 7 mins apart I woke OH. It might not take you long for them to reduce in time, or they might take ages, just see how it goes. If you ring your midwife/doctor around this time and let them know what's going on, they'll probably advise you sit in a shallow bath and/or take some paracetomal. I also got told to eat something as I would need the energy for later.
Once your contractions get to around 4 mins apart you'll be asked to go in. You might be told to go in earlier, this is just what happened for me. If you're in huge amounts of pain and feel you can't deal with it then go straight in. Once you're at the hospital/midwife centre or wherever you are giving birth, you're likely to have a little wait and then go into a labour room. The midwife/doctor will check how dilated you are. I used a birthing pool and as I was already 4cm by the time I got in, I got straight into the pool. If you're not using one, you might be told to walk around for a bit, or be offered pain relief etc. They'll also do other checks other than how dilated you are at this point too, check baby's heartrate, and probably yours too.
Once you've got past the labour you're on to the pushing. Your midwife/doctor will lead you and help let you know when to push. Listen to them

they know what they're doing and it will likely minimise any tearing. 'Hold your pushes' rather than totally relax, as otherwise baby will slip back in again. Once the head is at the opening, you'll feel the 'ring of fire' you basically just feel stingy 'down there', but push past it

this is the worst bit of actually pushing. Once the head is out, it's just the body to push out on the next contraction. Then you'll get to hold little one etc

and it's just delivering the placenta. You'll be offered an injection to encourage it to come out, if not you are given about an hour 1/2 (I THINK it was) to get the placenta out naturally - it should just come away on it's own, with some yanking on the umbilical cord from midwife, but sometimes it doesn't. If it doesnt you have the injection, and if it still won't budge you might have to have surgery to remove it. But usually it'll come away
Hope this helps!!!
xoxox