Q: There is a particular procedure for making istinja in islam which unfortunately I am not aware of because nobody taught me this. Please help me regarding this important issue.
A: If it is faeces then see that it is washed thoroughly and that there is no trace of it left behind and if it is urine then after washing up, pause for some time until the remainder urine is emitted. Thereafter, you could proceed to make wudhu.
And Allah Ta’ala (الله تعالى) knows best.