Question

could you explain the difference of seen and saw.Thankyou.

Answer 1

Saw is simple past tense. Yesterday I saw a bluebird. This morning early I saw horses in the field.

Seen is the past participle and is used in the "perfect" tenses. It always has to have another verb with it.
have seen(present perfect), has seen, had seen(past perfect), is seen, was seen, has been seen, etc.
I have seen blue birds often.
I had not seen bluebirds often.
The bluebird is seen in the spring.
A bluebird was seen in at the bird feeder.

Here is an excellent site on verb tenses.
http://owl.english.purdue.edu/handouts/esl/esltensverb.html