A Christian woman wants to fast
Question

I'm a christianity but I do not believe in my religion anymore,and i'm sorry for that. I believe in allaah and his prophet. Now I want to do the Rammadan,but I'm still christianity,can I do the rammadan now? I dont know how to be a muslim. I feel it in my heart but I think this is not enough?.
Praise be to Allah.We ask Allaah to open your heart to Islam.  
If you fast without entering Islam, you will not gain anything from it except hunger and thirst, because Allaah does not accept any acts of worship unless they are based on correct belief and sound religious commitment. 
The most important thing for you – and the most important thing overall – is to start with the right step, which is entering Islam.
 After that you can start to pray and fast, and read Qur’aan, and do all the acts of worship which will bring life and joy to your heart.  
It is not difficult for you to enter Islam, all you need to do is to utter the Shahaadatayn (the twin testimony of faith): Ash-hadu an laa ilaaha ill-Allaah wa ash-hadu anna Muhammadan rasool-Allaah (I bear witness that there is no god except Allaah and I bear witness that Muhammad is the Messenger of Allaah). 
The fact that you feel in your heart that you are already Muslim is a good sign, but you have to take the last and most important step, which will bring you happiness in this world and in the Hereafter. 
If you do not believe in your religion – as you say in your question – then what is life worth if a person does not have a religion or values or a divine system by which to live? 
Do you think that the life of this world is no more than leisure, idle pursuits and satisfying desires, then it all comes to an end when you die?
 No way! For after death comes the reckoning, and after the reckoning comes either Paradise or Hell. 
So you must hasten to do that which will lead to your salvation. Do not wait or hesitate, for life passes quickly and no one knows when his life will come to an end and he will enter the first stage of the Hereafter, where regret will be of no avail, and a man will wish that he could return to this world so that he could believe and do righteous deeds.
“Until, when death comes to one of them (those who join partners with Allaah), he says: ‘My Lord! Send me back,
So that I may do good in that which I have left behind!’ No! It is but a word that he speaks; and behind them is Barzakh (a barrier) until the Day when they will be resurrected”
[al-Mu’minoon 23:99-100 – interpretation of the meaning] 
“If you could but see when they will be held over the (Hell) Fire! They will say: ‘Would that we were but sent back (to the world)! Then we would not deny the Ayaat (proofs, evidences, verses, lessons, revelations, etc.) of our Lord, and we would be of the believers!’”
[al-An’aam 6:27 – interpretation of the meaning] 
“But those who disbelieve (in the Oneness of Allaah — Islamic Monotheism), for them will be the fire of Hell. Neither will it have a complete killing effect on them so that they die nor shall its torment be lightened for them. Thus do We requite every disbeliever!
Therein they will cry: ‘Our Lord! Bring us out, we shall do righteous good deeds, not (the evil deeds) that we used to do.’ (Allaah will reply:) ‘Did We not give you lives long enough, so that whosoever would receive admonition could receive it? And the warner came to you. So taste you (the evil of your deeds). For the Zaalimoon (polytheists and wrongdoers) there is no helper.’”
[Faatir 35:36-37 – interpretation of the meaning]  
We ask Allaah to guide you and to help you to do that which is good for you in this world and in the Hereafter. 
We are ready to answer any questions you may have in sha Allaah. 
And Allaah knows best.