In your how to pray you only mention Fardh? What about the sunnah Salah? Fajr 2,2 Dhuhr 4,4,2 Asr 4 Maghreb 3,2 Isha 4,2,3 But I don't know difference between Fardh and sunnah but apparently there is?
Fardh prayers are obligatory. They are the second pillar of Islam, and they must be done.
Sunnah prayers are those that are optional
Nafl prayers (supererogatory) are like sunnah prayers - optional, but have benefits.
The ones you are referencing are Al Sunnan Al Rawatib (Sunnah Prayers Associated with Fardh Salah)
“Allaah will build a house in Heaven for whoever is diligent in observing 12 SunnahRak'aat (as follows): 4 Rak'aat before and 2 after the Dhuhr (Midday) Prayer, 2 after theMaghrib (Sunset Prayer), 2 after the ‘Ishaa’ (Evening) Prayer and 2 before the Fajr(Dawn) Prayer.” [Sahih Tirmidhi]
The Prophet(May peace and blessings be upon him) in saying: “MayAllaah have mercy on one who prays 4 raka’aat before the ‘Asr Prayer.” [Tirmidhi]
Note: These are prayed in sets of 2 (so for the 4 before Asr it is 2 then 2) preferably. However, one could pray them all in one set (one tasleem).
The time for a sunnah prayer that comes before a fard prayer is from the beginning of the timefor that prayer, until the iqaamah.
The time for a sunnah prayer that comes aftera fard prayer is from after the salaam at the end of the fard prayer until the end of the time for that prayer.