You need to be sure that its water leaking and not something else.
Condensation can cause this, as can a young person who still isn't good at aiming....
If it's not the above, you need to dismantle the rear cabinet completely and expose the toilet and its gubbins in full.
Then, watch and see exactly where the leak is.
If it's the water in, that's plumbing. Not impossible but you need to see why before you look to fix it.
If its the waste out, likewise, you need to see the problem before you fix it.
If this is a recent install, then that would point to a poor installation and error.
If it's been around for a while, it could be something has shifted or worn out.
Fixing it isn't hard. Identifying the yrue cause is the hard bit.
If you think you are good for that and have tools, go at it.
If you are not comfortable with Diy, then likely this isn't a quick, simply fix (could be though!) so look to get a plumber in.
Toilets can get out of hand quickly if you are not handy.
Best of luck.