Kindly inform me how could I transfer the money from UK and I'm working there for 4 years and does it cost the tax and how much.
how could I transfer the money from UK
There are multiple ways, walk into your Bank and ask them to wire transfer to the Bank Account in India. You would need the SWIFT BIC of Bank in India, Account Number, etc.
Quite a few Banks [State bank of India, HDFC, ICICI etc] also offer remittance service. Visit their website for more details.
does it cost the tax and how much
Assuming your status is NRI [Non Resident], there is no tax implications of this in India.