need help

I have a 1995 concord and i was wondering if i put stop leak in would it stop a leak in my freeze plug?

vickeysaber, my strong advice to you would be to have your car properly repaired by a
competent technician by having the leaking frost plug replaced as well as having the rest
of them checked out for a similar condition.
There is a problem with pouring sealing products into the engine with the side effect of
plugging up the car's heater core as it is also a part of the cooling system.
If you are determined to put that stuff into your engine you should take the precaution
of disconnecting the heater core from the treatment by removing the heater hoses and
joining them together using a short length of pipe so that the engine can be run.
Most people cannot be bothered doing this as it is too time consuming, or too messy, or too
bothersome. Then when it's cold enough to turn on the defrost or the heat there isn't any,
as the heater core is flowing very little coolant. Now you need a new heater core as no
amount of reverse flushing will clear it out.
A point of caution when removing the heater hoses; DO NOT TWIST the hoses off of the
heater core inlet and outlet tubes! A large percentage of the time that will result in
breaking off the tubes, and you only have to break one. Then you will need a new heater core.
To remove them successfully and safely, cut the heater hoses just to the end of where they
push on to the heater core tubes. Yes, I mean cut them, sever them completely. Now you only
have to deal with the inch or inch and a half of hose that is actually left on the tubes.
Now you can gently remove the hose clamps from the remaining hose by expanding them enough
to slip them the short length of the hose that has yet to come off.
With the hose clamp now removed, take a razor blade and cut the short section of hose on the
tube along its full length, from end to end. Now you can spread the hose open and "peel" it
off the tube with absolutely no torsional stress to the tube. The heater core is safe and
ready for the hose to be reattached. This would also be a good time to replace the heater
hoses as they're probably due. To put the hose back on you can lubricate the tube of the
heater core with some waterless handcleaner or some liquid dishsoap and PUSH the hose on.
DO NOT TWIST the hose! Then install the hose clamp and tighten it moderately. Check for leaks.