Just discovered that s pipe in the basement ceiling is wet, found a leak from the metal seal that joins the floor and pipe on the upstairs bathroom toilet, the toilet was recently pulled up to install new flooring and then put back down but it hasn't been sealed to the floor all the way yet and it was recently used by mistake and now its leaking, how can I fix it myself?

Did you install a new wax ring? If not, remove the toilet, clean the bottom of the toilet and the flange and install a new wax ring. Let's assume you have used a new ring: you mentioned you installed a new floor, if you installed a new subfloor like a 1/4" Luann, it is possible you didn't raise the flange. If that is the case, you may be able to use a jumbo ring to compensate for the additional 1/4", it really depends on the height of the existing floor flange. The flange should be resting and seated then secured on top of your subfloor. If you cut the subfloor around the existing flange without raising it the additional 1/4" , then you can try using the jumbo wax ring. When reinstalling he toilet and new wax ring, make sure the wax is soft and pliable, if it is cold and hard let it sit in a warm area, this wax needs to be able to settle to both the toilet and flange simultaneously to create a good seal. Center the toilet over the new bolts and flange, then using your body weight, apply pressure all along/around the sitting area of the toilet until it feels like the toilet has bottomed out. Install the nuts to the anchor bolts and snug down, being careful DO NOT TO OVER-TIGHTEN. Re-connect the supply line, snug the fitting tight, cross your fingers and turn on the valve. Good luck