I agree with the post above, doing piercings yourself rarely end well. But if you really don't want to tell your parents, I highly recommend using the antibacterial soap (dial is the best) very often, multiple times a day.
Also I have my naval pierced (professionally though), && I was told to use the salt water spray, H2Ocean. It will help the piercing heal faster && should also help with the infection. A naval piercings usually takes anywhere from 6-9 months to heal, && if you intend on keeping it you shouldn't remove the rod that's already in there until it does fully heal.
If you are to start getting a puss bubble, that's normal. Mine ended up getting that, && I asked the piercer about it, he told me that didn't mean it was infected, it just happens && he advised me to just pop it, && try to get all the puss out.
Be very careful though, if you pierced only a small amount of skin, wearing heavy dangly jewelery can make your skin eventually stretch && break.
Next time I highly recommend you get piercings done by a professional, but good luck && I hope you can make the infection go away.