I recently met Sheik Hisham and took biya, yet I am still a little unsure of what the whole thing means.
In the name of Allah the most Beneficent and Merciful.
Bay`ah is to give oath or allegiance to a Sheikh for spiritual guidance. This is the way of the Sufis to ensure that the Barakah and blessings are passed down through a saint from the beloved Messenger of Allah (May Allah bless him and grant him peace).
It is evident when the companions gave Bay`ah under the tree of Ridhwan to the Messenger of Allah to live and die for Islam. The spiritual path (Silsila Naqshband) in your case will provide you with certain prayers that should be said to obtain closeness with Allah.
You should remain loyal to your Shaikh and obtain guidance from him. Some of the recognized established Tariqas are Qadiri, Naqshbandi, Sohawardi, Chisti, Shadhili, Razvi, Ashrafi etc. All lead by great saints of their time to obtain the path to Allah.
Of course Allah knows best
[Answer provided by: Muhammad Salim Ghisa]