I do know I need to get a new flapper eventually, installing it is just going to be the interesting part...I haven't the slightest idea how and the one person in this household who does rarely has any free time.
Flappers are about the easiest thing on a toilet to change*. You don't even need tools.
1. Go to store and buy a flapper. Last I looked they were about $5. Avoid black rubber, as they tend to get black slime stuff. Still works fine, it's just disgusting when you change it again.
2. Remove top from toilet tank.
3. (optional) Turn off water at valve under toilet. To be honest, I just let the water run, since this is a pretty quick fix.
4. Flush toilet to empty tank.
5. Remove old flapper. It has been a while, but I seem to recall it was held on by side loops.
6. Detach chain from old flapper.
7. Attach chain to new flapper.
8. Loop the loops over the loop holders.
9. (Turn water back on if you turned it off.) Test flushing a couple of times to make sure the chain is pulling up the flapper properly.
*This is assuming that you don't have a really fancy or unusual toilet. I have no idea how to change the flapper on a Toto with all the accessories. I'm not even sure if Toto toilets have flappers.