Please give me some points on 'To forget and forgive in Islam'.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If what you mean is to overlook people's faults and sins and conceal what you see, this is asked in Islam. Muslim reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "Allah is in the help of a person who is in the help of his brother" .
Ahmad and Abu Dawood reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "O! You the community of those who said by their tongue that they are Muslims but the faith has not entered their hearts do not harm Muslims and do not follow up their faults. Indeed any person who follows up the faults of his fellow Muslim brother, Allah will follow up his own faults and if Allah follows up the faults of a person, He will uncover his faults in his own home" . Allah Says (interpretation of meaning): {… And spy not, …} [49: 12]. This means take what is apparent and do not track the Muslims' faults, i.e. nobody should seek to know the faults of his brother. On the contrary, he should conceal any defect or fault he noticed from his brother.
As for forgiveness, Allah has praised people who forgive. Allah Says (interpretation of meaning): {…, and who pardon men; verily, Allâh loves Al-Muhsinûn (the good doers).} [3: 134]. Forgiveness means to relinquish a right that you have on somebody or not to punish somebody for something wrong he did to you. Forgiveness is among the good morals and the noble characteristics which make the person more honourable and prestigious.
Muslim reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "Abu Hurairah reported Allah's Messenger (may peace be upon him) as saying: Charity does not in any way decrease the wealth and the servant who forgives; Allah adds to his respect, and the one who shows humility Allah elevates him in the estimation (of the people)" .
al-Baihaqhi reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "A caller will shout on The Day of Judgment saying: Whoever has a reward on Allah should enter Paradise". It is then said: "Who are the ones whose reward is on Allah?" Then the forgivers stand up and enter Paradise without trial" . Abu Naim mentioned a Hadith or a tradition from Ali Ibn al-Hussein about the merit of forgiveness saying: "On the Day of Judgment a caller will say: 'Who amongst you are the people of kindness?' Then some people stand up. It is then said to them: 'Go into Paradise'. The Angels meet them and ask them: "Where to"? They reply: "To Paradise". The Angels say: "Before being judged"? They reply: "Yes". The Angels ask: "Who are you?" They reply: "We are the people of kindness". The Angels ask: "And what was your kindness?" They reply: "We used to be clement when oppressed and be patient when aggressed and forgive when offended". The Angels then say: "Enter Paradise how excellent a reward for the (pious good) workers!" .
Allah knows best.