Before you learn how to make wudu you should know to preform Istanja, and how to. So what is Istanja?
WHAT IS MEANT BY "ISTANJA"?
Istanja is an Islamic term for getting rid of uncleanliness. It is a method of cleaning one's self with water after using the toilet.
If you have grown up using toilet paper, think of how we clean a baby when changing its diaper. Do we merely use toilet paper on a baby? No, we usually use a wet wipe, because it is cleaner to have something "wet". Toilet paper on its own is only a wiping device, not a sanitary one whatsoever, so unfortunately, what adults intrinsically think of when caring for infants, is forgotten when caring for themselves or training their children.
In Islam, even cleaner than a wet wipe, we use a spray of water to clean ourselves after urination or after using a wiping device in the case of defacation. If you have not performed Istanja after using the toilet before making wudu, your wudu is not valid, and so your salat will be invalid. It is also a sin and there is punishment from Allah subhanahu wa ta'ala for neglecting it as is related in this sahih hadith (may Allah subhanahu wa ta'ala protect us from such things, ameen) :
Ibn Abbas (Allah be pleased with him) narrates: " The Messenger of Allah (Allah bless him & give him peace) once passed by two graves and said: "They (in the grave) are being punished not for a great thing to avoid" Then he added: "Yes, (they are being punished for a great sin), for one of them used to go about with calumnies while the other never saved himself from the splashes of urine"
But who would want to keep on using toilet paper now that they have learnt the benefit of performing istanja with water?!!!
HOW TO DO ISTANJA WITH #1 (urine):
After urinating dry the urine with a clean piece of mud (for those in a country without toilet paper) or toilet paper and then wash with water.
HOW TO DO ISTANJA WITH #2 (you know):
Clean the private part with three or five clean mud pieces (hey, that's how they did it historically) or toilet paper and then wash with water.
WHEN TO MAKE ISTANJA?
After using the toilet for number 1 or 2.
WHICH HAND SHOULD BE USED FOR ISTANJA?
The left hand should be used for all acts of wiping in rinsing during istanja. It is a sin to use the right (which has to do with eating and taking meals, which is a subject that will be broached at a later date). In Islam know, that for every good thing the right hand is used, and everything else the left if used.
AND APPARENTLY THERE HAD TO BE A RULING ON THIS
By what things Istanja should be done? By toilet paper, clean mud pieces or stones, and finished ALWAYS with water. By what things should it not be done? With bones, or food, coal, or writing paper (i.e useful things should not be ruined for the sake of a wiping device).
Helpful notes for people not living in a Islamic country with Islamic toilets with spray devices like the one pictured below or bidets: carry a water bottle (that you won't use for drinking or let anyone else drink!!!!!!) or a small container of water with you in your purse when you go out prep for public washrooms and the like, and at home, keep a watering can (some of my Muslim sisters I have visited use these) or, as I prefer, a water spray bottle (the kind you use for your hair) from the dollar store and keep it beside the toilet. If you can, get a shower spray installed for yourself.
Source: Girls Guid To Being Muslim
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيمِ