объясните пожалуйста вкратце при каких условиях применяются окончания -ing и -idi в англ. яз.

Вы, очевидно, имели в виду окончание "-ed". Это окончание добавляется к правильным глаголам при образовании форм:
Past Indefinite - We played tennis yesterday.
Past\Present Perfect - She has finished her work.
Passive Voice - The book was published last year.
Participle II - I bought the book published last year.

Вот так, в общих чертах.

Может быть, ты имеешь ввиду окончание -ed?
-ing может обозначать какое-нибудь длительное время глагола (I am reding a book now), отглагольное прилагательное (It's a writing paper), причастие (He said it entering the room), герундий (No smoking)
-ed может указывать на какое-то прошедшее время (He entered the university last year), причастие (The girl dressed to the latest fashion was cool), на пассивный залог (The boy was looked at in surprise).
Всё зависит от места в предложении и рядом стоящих слов.
Конкретизируй вопрос, тогда можно будет объяснить яснее.

The –ing form can be used like a noun, like an adjective or like a verb.

Smoking is forbidden.
I have a long working day.
I don't like dancing.

When it is used like a noun it may or may not have an article before it.

Marketing is a very inexact science.
The marketing of the product will continue for a few months yet.

It can also be part of a 'noun phrase'.

Speaking to an audience is always stressful.
Swimming after work is very relaxing.

In formal English, we would use a possessive with the –ing form. In informal English, many people do not.

I'm angry about his missing the meeting.
Do you mind my coming?

As an adjective, the –ing form can be used before a noun.

I was met by a welcoming party at the airport.
Let's go to the meeting room.

The –ing form is used after prepositions.

Before leaving, you need to speak to Sarah.
After discussing it with her, I've changed my mind.
Instead of feeling sorry for yourself, do some work for charity.

Notice that when 'to' is used as a preposition, it is followed by the –ing form.

I don't object to working this Sunday.
I'm looking forward to seeing him again.
I'm used to working long hours.

There are many verb + -ing combinations. Here are some common ones:

I admit telling her.
I appreciate having the raise.
I avoid speaking to him.
I consider blowing your nose in public to be wrong.
I delayed coming until the last possible moment.
He denied telling her.
I detest going to parties.
I enjoy dancing.
I feel like having a party.
I've finished writing the report.
I've given up going to the gym.
I can't help thinking about it.
I can't imagine ever leaving this company.
I don't mind doing that.
He put off talking to her as long as he could.
I can't stand drinking beer.

Some verbs can be followed by either the infinitive or –ing form but with different meanings. Here are some common ones:

I stopped smoking last month. (I no longer smoke.)
I stopped to smoke a cigarette. (I stopped what I was doing and had a cigarette.)
I remember telling him. (A memory of the past.)
I must remember to tell him. (Something to remember for the future.)
I'm interested in finding out more details. (Interested about the future.)
I was interested to read his report. (Interested in the past.)

Some verbs can be followed by either the infinitive or –ing form but with the same meaning. Here are some common ones:

I love to go shopping.
I love going shopping.
I'm afraid to fly.
I'm afraid of flying.
I started to learn English 5 years ago.
I started learning English 5 years ago.

Это разные вещи. С idi что-то не так. Это редкое окончание имен собств. , может элементов. ed - другое дело, показывает завершенное действие в конкретный момент прошлого.
ing же вам уже популярно объяснили