Put around a 3rd of your starter in a bowl add flour and warm water to the quantity required. Mix together into a dough this should not be runny in any way but should not be super dry hopefully it will be sticky to touch and be less sticky after left to sit, you will work this out over time.
Place the dough into a loaf tin leave in a warm place next to a radiator works well, after around 6 hours it should have doubled in size this varies greatly depending on the amount of heat.
Place the expanded dough into a preheated oven at 220 degrees for 10 - 15 minutes the bread should rise even more then reduce the heat down to low to finish use a skewer to check if unsure it should come out clean.