i started playing the bassoon i can play alway the to f on the 3 line how you get high and how you play half hole

To play a half hole, simply move your first finger left hand along just a bit so part of the hole is uncovered. Uncover a lot for F#, a little bit less for G. Try different positions until you find the ones that work best on your horn.

As Drew says the opening does vary from note to note & between instruments.

I roll my finger slightly to get the required opening. This does take some practise - even after 25 years I don't always get it right! I would suggest a starting point is to play the bottom octave F#, G or G# then experiment with rolling the left first finger until you manage to consistently get the upper octave. You will need to use slightly more air pressure as well but do not squeeze the reed at the same time.

When this works you can try going from another of the lower notes - say C (2nd space) - & then eventually go for the hardest F (No fingers) to a half hole note (most fingers down)

Good luck.

Ian