How to take Syahadah?
Those who wanted to become a Muslim, taking the syahadah or the Islamic oath is the most important step in your life. Once you take the syahadah, you will not have a single sin with Allah anymore because you are just being repented. You are just like a baby being reborn. Your future life is a bright white page for you fill in. You are also been granted with an atomic size of reward in which you are guaranteed the lowest level of paradise with Allah blessing.
مَنْ شَهِدَ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ وَأَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ وَأَنَّ عِيسَى عَبْدُ اللَّهِ وَرَسُولُهُ وَكَلِمَتُهُ أَلْقَاهَا إِلَى مَرْيَمَ وَرُوحٌ مِنْهُ وَالْجَنَّةُ حَقٌّ وَالنَّارُ حَقٌّ أَدْخَلَهُ اللَّهُ الْجَنَّةَ عَلَى مَا كَانَ مِنْ الْعَمَلِ
"Whoever testifies that there is no god worthy of worship except Allah alone, without any partners, and that Muhammad is Allah servant and messenger, and that 'Isa (Jesus) is Allah servant and messenger, and Allah word which Allah conveyed to Maryam (Mary), and a spirit created by Allah, and that Paradise is true and Hell is true, Allah will admit him into Paradise, regardless of the deeds he has done." Bukhari (3435)
From a hadith by ‘Ubadah, Muhammad (peace be upon Him) said:
It is recommended for a person to take syahadah in front of an Imam or any Islamic authority. It is also recommended for you to bring a long your trusted muslim friend to become a witness. Your Imam and/or your trusted muslim friend will become a witness of your syahadah in front of Allah in the day of judgement later. The syahadah needs to be taken using arabic language.
Meaning:
I bear witness that Allah is the ONLY GOD and I bear witness that Muhammad is a MESSENGER of Allah.
Once you have taken the syahadah, you will need to maintain the faith. You will need to say it over and over again in many situations such as:
At the beginning and inside every prayer
Before you go to sleep
When you are dying and at the brink of your death
At any situation that suits you
When you miss Allah and Muhammad