couple of questions on PH

[Ceelo]

I am kind of confused on this subject. I understand that the PH should be anywhere from 6-7, 6.5 being the best. I understand that limestone should be used to raise the PH. The PH is raised when fertilizers are creating salts and other substances in the soil. Now the part that confuses me is, what am I suppose to use to lower the PH if it gets to high? What website is good for getting limestone. How much am I suppose to use to raise the PH one level? How do I get rid of these salts that are harmful to the plants? Someone told me to flush the soil until the water comes out clear from the drainage holes, doesn't that cause overwatering? I am sorry for asking so many questions but it would be of great help if they are answered.

[Ceelo]

can anybody help