I,am 18 years i want to increase my height to 6.3 inches

May be too late but: I am sorry to tell you that most men stop growing around age 18- but occasionally some will grow until age 21 or so. Taking measures to increase your production of growth hormone might help, but if your growth plates have closed (like most 18 yo's) then you've reached your max. See "http://www.thebodywellusa.com/blog/dr-mike-carraghers-top-10-ways-to-increase-your-human-growth-hormone-hgh-levels".

Unlikely to happen: By 18 most males are at the end of their linear growth ; their growth centers are closed.An x-ray of the wrist/hand can show if your growth centers are open to more.If you entered puberty late and have a bone maturity more like a 15 yo you may get 2 -3 inches.Balanced diet/rest/exercise all help.If your growth centers are closed, you are done.You will need to accept your height as it is.