How can I get the water to shut off so I can fix the toilet

There should be "angle stop" valve about 6" above the floor, on the left side of the toilet. If it doesn't function properly and you cannot close it all the way, go in front of your house and turn off main shut-off valve for whole house. Do your repairs and when finished , turn water back on.

Like Milo says close the angle valve under the toilet tank, see the picture I have marked the angle valve for you, Thanks.

John