How do i fix a 2000 kia sephia that turns over but wont start?

sorry to tell you but you have a blown headgasket or cracked cylinder head. that is why the coolant blows out of the radiator and the engine won't start due to engine compression getting into the cooling system.

crank senser look on you tube

Is it a whine or a clicking sound? Could be the starter, could be a fault in the fuel delivery system. This could a number of issues.

well if it is cranking its not starter or battery . maybe check to see if fuel pump is working .check fuses. you should be able to hear pump run for a few second . if pump working maybe fuel filter or sensor like throttle position ,air idle sensor. make sure all wires are hooked up on alternator & starter . no vacuum hoses off any where . is check engine light on ?

It could be a lot of things but I would be very suspicious of the starter and flywheel. The fact that it will start with a push suggests that your codes are not the problem with starting. Your starter's bendix drive could be weak which means it will disengage before the car starts. The solenoid could be getting worn and not putting enough juice to keep the starter running. The flywheel could have a "flat" spot.
To check the flywheel for a "flat" spot you will have to look at it and turn it by hand. The best way is to use a screwdriver or small pry bar and work it around that way. You are looking for missing teeth, teeth that are ground off or narrower than the rest. If you find that the flywheel needs to be replaced. I would try to start the car and when the starter kicks out, start looking right there.
The only way I know of testing the starter and solenoid is to replace them and see if that works. Hope this helps.

sounds like either the teeth on the flywheel or on the starter itself are missing a few gears or the sylinoid is not ingaging the starter enough

Doesn't sound like starter is engaging fully with flywheel, is that correct? You may have to shim it a little one way or another to get it properly aligned. When starter off, did you take a look at teeth on flywheel to see if worn off perhaps? With key off, try turning engine over by hand slightly to allow for different position on flywheel and see of that works.

check your alternator for proper charge, about 14.6 v

Sounds like a short in your starter.Get it checked.

If it is a manual trans could be nuetral saftey switch but other then that check grounds at the bettery and engine .Still could be starter like you said flat spots on it hope this helps.