It is correct, I can confirm you stil need an online application before proceeding to Gerry's.
https://www.konsolosluk.gov.tr/
This is the right website. Fill up the form, put all the correct details and at the end, submit relevant documents. You will receive a reference number in your email while you are going through the process, don't just take the number and stop, rather finish the complete form.
For the invitation letter, ask your friend to look for any public notary, they are very common in Istanbul, there the people will guide her.
For the bank statement and parents support, go to City Court and get a statement by your parents stating all details that they will support you and bear your expenses then get it notarized by the court.