I am building my own website and I want to use my picture to explain Hijab and its benefit in Islam.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

You are not allowed to put your picture on Internet for many reasons.
a) A woman is asked to cover herself and stay at home. Allah Says (interpretation of meaning): {And stay in your houses, and do not display yourselves like that of the times of ignorance, …} [33: 33].
The Prophet (Sallallahu Alaihi wa Sallam) said: "You are permitted to go outside for your needs" . [Reported by Imams al-Bukhari and Muslim ].
The Hadith proves that if there is no need, a woman should not go outside since by doing so she exposes herself and others to temptation. The Prophet (Sallallahu Alaihi wa Sallam) said: "A woman is Awrah (i.e. should be covered) if she emerges the Satan makes people to raise their glance towards her" . (i.e. makes her attractive for men or tries to seduce her). [Reported by Imam al-Tirmizi and regarded it Hasan].
No doubt, the appearance of a woman's picture on the Internet seen by everyone is more dangerous than going out for necessity with complete Hijab. Also, a picture is not compulsory since the Hijab can be easily described in words.
Allah knows best.