Ablution?

Peace bro, basically Ablution or wudu is the Islamic act of washing parts of the body using water. Muslims are required to be clean in preparation for ritual prayers. The Qur'an says "For Allah loves those who turn to Him constantly and He loves those who keep themselves pure and clean."

These are the permitted water types for performing Ablution (basically any source of water after verifying it's pure and clean):
- Rain water
- Well water
- Spring, sea or river water
- Water of melting snow or hail
- Water of a big tank or pond

O ye who believe! when ye prepare for prayer, wash your faces, and your hands (and arms) to the elbows; Rub your heads (with water); and (wash) your feet to the ankles. If ye are in a state of ceremonial impurity, bathe your whole body.

Invalidation

Theoretically, one can perform one wudu for salaat and this wudu would be considered valid for the rest of the day. However, certain acts invalidate the wudu (often referred to as "breaking wudu") and these can be stated generically thus:

Defecation, passing gas or urination
Emission of semen
Sleep while reclining
Vomiting
Loss of senses
Fainting
Laughing aloud whilst in Salah
Sexual contact with another person (ghusl [Bath] is required)
Some consider the below actions will also invalidate wudu,

Touching the private parts with the bare hands
Blood or pus leaving the body so that it leaves the point of exit (however if the blood or pus exits from the private parts than any amount breaks wudu)
Touching a mature person of the opposite gender that is not your blood/milk relative (i.e. your spouse)

Ghusl (غسل) is an Arabic term referring to the full ablution (ritual washing) required in Islam for various rituals and prayers. This type of ablution becomes mandatory for any adult Muslim after having sexual intercourse, any sexual discharge (e.g. of semen),completion of the menstrual cycle, giving birth, and death by natural causes.

Islam also recommends (i.e. it is mustahab) the performance of the full ablution before the Friday and Eid prayers, before entering the ehram, in preparation for hajj, after having lost consciousness, and before formally converting to Islam.

The same type of water types in Ablution are also applicable to Ghusl.

Farā'id or obligatory acts that must be performed in Ghusl. These are three fard acts. If one of these acts is omitted, it must be returned to and then completion of the successive acts are to be performed.

Rinsing the inner mouth.
Sniffing water and blowing it out.
To wash the entire body in such a manner that not even an area equal to a strand of hair be left dry. If this is not done properly, then Ghusl will not be done.

Optional requirements (or the way practised by Muhammad according to Sunni Hadiths) of ghusl:

Washing both the hands up to the wrists.
Wash the private parts and remove dirt or filth from the body.
Perform Wudu.
Water should be poured over the head three times so that it flows all over the body.

A scholar, Muhammad ibn Saalih al-Uthaymeen said, "Sufficient ghusl means that you rinse your mouth and nose, then you wash your entire body with water, even if that means plunging yourself into deep water in one go.

If, after Ghusl, one recalls that a certain portion of the body is left dry, it is not necessary to repeat the Ghusl, but merely wash the dry portion. It is not sufficient to pass a wet hand over the dry place. If one has forgotten to rinse the mouth or the nostrils, these too could be rinsed when recalled after Ghusl has been performed.

As for if Ghusl has to be performed immediately after ceremonial impurity, i don't know, but it certainly has to be performed before praying.

Peace again

There are two things you need to know. There is ghusl and then there is wudhu (ablution).

Ghusl is required after one gets into a stage of major ritual impurity. E.g. after sexual intercourse (please be aware that there are other things that necessitate it too).

After you have performed the procedure of ghusl, that's it. You're likely to always be in a state of major ritual purity until it is broken but you don't need to do ghusl before each prayer.

However, wudhu/ablution must be performed in order to pray any of the 5 daily prayers and before being able to touch and handle the Quran.

One cannot simply perform wudhu whilst he is in a state of major ritual impurity (i.e. when ghusl becomes necessary).

If you live in an area that is close to mosques then I would advise that you join up for classes to learn these things from scholars/imams. It would just make it difficult for yourself to learn from books alone.