i know theres a article on UG but i still don't really understand it.can some one elaborate or explain it more straightforward? if theres a good video on it can you plzm share thnx
Hammer on.....

Usually you play a note and then hammer on the same string to a different note.
Like just fret the next note you want to play without picking.

Pull off is the exact opposite.
You have two notes fretted , pick and then pull your finger off to the note you want to ring out.
You should slighty pull down on the note you're pulling off from. Just lifting your finger off isn't as effective.

Hopefully that was clear.... I'm sure there are some youtube vids on it if you search.
There is nothing to it. for example to pull-off...

put 2 fingers on the 11 and 12th fret of any string. now play it and lift the finger that is on the 12th fret. that sound that comes right after you pull off is a "pull-off".

Hammer-ons are just the opposite
okay its this simple
fret a note any note then while its still ringing pull the finger of a string kinda flicking it to keep the note ringing
like so
p means pull of
so put one finger on 8 and another on 7 and pull the finger off and the note sound still be ringing lower af course
and hammer on is the opposite of that
Hammer-on = fretting a note and getting it to sound without picking it.

Pull off = Fretting a note, say 14 on the first string, while also having a finger on a lower fret on the same string, say 12. So you pick 14 and then literally pull your finger off the string while leaving your finger on 12 the whole time.

If you want a video lesson just search on Youtube, there are over 9000 of them. For example, http://www.youtube.com/watch?v=sbS53hy2JUk
I haven't watched that one, but judging from it's title it should be what you're looking for.
You'll probably find hammer ons easier than pull offs, there is a tendancy to brush against other strings so i'd recommend starting on the bottom (thinnest) e string as there's nothing to pull off against.
Repetitious postage much?

I find that it helps with 3-4 note legato runs to almost twist my wrist a little bit, especially on the pulloffs.
"If you're looking for me,
you better check under the sea,
because that's where you'll find me..."
People in this thread seem to forget that if you don't tell the OP to pull off PROPERLY he will just lift his finger off the string, which ends up being a shitty deadened version of a pull off. You need to ensure the note is sounded by slightly plucking it as you leave... and even 'plucking' is a bit of a harsh word.
: )
Like a lot of techniques it's easier on some strings, frets, etc.

Practice your pull offs on the high e (thinnest) string. Fifth to third fret or so. Don't get bogged down in details. Repetition will 'get it'. Your ear will tell you whan you pull too much or too little string.