About -ING (you can try to help/helping)

[Thoryr]

There must be a rule I cannot get about ING, I explain. When somebody says 'I'm looking forward to hearing from you' where is the rule here that obliges you to put ING? The same with TO + verb + ING like to being. How come you have to + Ing? Is there an easy way to understand it?

The same regarding 'you can try to help/helping'. I kind of understand it but I cannot explain it and that bugs me. Can someone give me something about ING to get rid of all the question marks right up in my mind?

[Mister Micawber]

.
In this kind of verb + verb situation, the 'to' is usually the infinitive particle:

I tried to help.
We wanted to go.
He liked to dance.
etc.

However, 'look forward to' is an idiomatic phrasal-prepositional verb, and 'to' is a preposition. Here are most of the phrasal-prepositional verbs with 'to':

I look forward to hearing from you.
I have to face up to meeting my ex-wife
We put our defeat down to batting so poorly.
I have to get down to studying soon.
.
_________________
Native English teacher at Mister Micawber's

[Thoryr]

Thank you! But what is the rule that applies when you say, for example " I have to go to my neighbour's house to try helping him out setting up his TV" ?

[Milanya]

Gerunds and infinitives can both be used as subjects, subject complements, and direct objects of verbs.

The choice between which to use as a direct object is sometimes dictated by the verb, leaving no choice. Which verbs can be followed by gerunds, which by infinitives, (and which by either) must be memorized.

http://www.iei.uiuc.edu/structure/structure1/gerinfvbs.html
_________________
con·text - The part of a text or statement that surrounds a particular word or passage and determines its meaning.