For tourist visas, there is no need to apply in advance or to fill in any forms. If you are flying to Turkey, you will buy your visa at the Turkish airport on arrival. You will see the visa desk, situated just before passport control. You must buy your visa, which will be stuck into your passport by the official, before you join the queue for passport control.
Visas are multiple entry and are valid for 3 months. Each passport holder must purchase a visa including infants. Tourist visas do not give you the right to take up paid or unpaid employment or to reside, or to study or to establish yourself in business in Turkey.
British overseas citizen passport holders and other nationalities should contact the visa section of the Turkish Consulate to check visa requirements.
Please follow the link https://www.evisa.gov.tr/en/ to apply and get your e-Visa online.