Hi,

There are 2 situations that I know where you use a verb with an -ING :

1. Present Continuous or Progressive.

     form:  present be verb + Verb-ING

               am singing

               is singing

               are singing

     - used when you are doing the action at the time of speaking.

    example:  I am typing right now.

     - used when you are in the middle of doing something.

     example:  I am reading a novel.

               At the time that I was saying this sentence, I am not actually reading the novel at that moment, but I read the novel before I said the sentence and I will go back to reading the novel. Therefore, I am in the middle of reading the novel (middle of doing something).

2. Past Continuous

     form:  past be verb + Verb-ING

               was singing

               were singing

     - used to describe an action happening in the past when another action took place within that period

     example:  We WERE DRINKING beer when my father asked for my help to find his key.

               In this example the first action happened (were drinking) and within that time that the first action was happening another even took place (asked for my help).

example

"I was helping my father find his key" alone is incorrect.

but if "I was helping my father find his key" was followed by an action that happens while this action is happening, say "when he asked me to drink beer." it will make the sentence correct.

I helped my father find his key. is simple past and uses a past verb (helped), which is used when an action is finished/stoped/over.

I hope you find this answer helpful.

You can message me on skype for more info (aaaJENaaa)