The present participle of most verbs has the form base+ing and is used in the following ways:

a. as part of the continuous form of a verb
(See continuous tenses in Present Continuous Tense)

Example:

I am working,
he was singing,
they have been walking.

b. after verbs of movement/position in the pattern: verb + present participle

Example:

• She went shopping
• He lay looking up at the clouds
• She came running towards me

This construction is particularly useful with the verb 'to go', as in these common expressions :

to go shopping to go ski-ing to go fishing to go surfing

to go walking to go swimming to go running to go dancing

c. after verbs of perception in the pattern:
verb + object + present participle

Example:

I heard someone singing.
He saw his friend walking along the road.
I can smell something burning!

NOTE: There is a difference in meaning when such a sentence contains a zero-infinitive rather than a participle. The infinitive refers to a complete action, but the participle refers to an incomplete action, or part of an action.

Compare:

• I heard Joanna singing (= she had started before I heard her, and probably went on afterwards)
• I heard Joanna sing (= I heard her complete performance)

d. as an adjective

Examples:

amazing, worrying, exciting, boring.

• It was an amazing film.
• It's a bit worrying when the police stop you
• Dark billowing clouds often precede a storm.
• Racing cars can go as fast as 400kph.
• He was trapped inside the burning house.
• Many of his paintings depict the setting sun.

e. with the verbs spend and waste, in the pattern:
verb + time/money expression + present participle

Example:

• My boss spends two hours a day travelling to work.
• Don't waste time playing computer games!
• They've spent the whole day shopping.

f. with the verbs catch and find, in the pattern:
verb + object + present participle:

With catch, the participle always refers to an action which causes annoyance or anger:

• If I catch you stealing my apples again, there'll be trouble!
• Don't let him catch you reading his letters.

This is not the case with find, which is unemotional:

• We found some money lying on the ground.
• They found their mother sitting in the garden.

g. to replace a sentence or part of a sentence:

When two actions occur at the same time, and are done by the same person or thing, we can use a present participle to describe one of them:

• They went out into the snow. They laughed as they went. They went laughing out into the snow.
  
  
• He whistled to himself. He walked down the road. Whistling to himself, he walked down the road.

When one action follows very quickly after another done by the same person or thing, we can express the first action with a present participle:

• He put on his coat and left the house. Putting on his coat, he left the house.
  
  
• She dropped the gun and put her hands in the air. Dropping the gun, she put her hands in the air.

The present participle can be used instead of a phrase starting as, since, because, and it explains the cause or reason for an action:

• Feeling hungry, he went into the kitchen and opened the fridge.
  (= because he felt hungry...)
• Being poor, he didn't spend much on clothes.
• Knowing that his mother was coming, he cleaned the flat.

Source: http://www.edufind.com/