how do i get my hibiscus to flower.

Most Hibiscus are dead easy, especially H.syriacus.
Fundamentally, all they need is plenty of sunshine and . . . . . . . ah, you're not living in Uk are you?
If you are . . . MOVE!
They don't like chilling winds either, so if moving isn't an option, try a well sheltered spot that has the potential to recieve as much sunshine as possible during the day, especially around midday onwards, and give a good dose of water and feed weekly.
In the tropics, they grow like weeds, even in locations that receive little rainfull for 2/3rds of the year, then they are deluged for the remaining third.
It's probably sunshine and a lack of nutrition.

Hibiscus can be quite fussy and will only flower if their requirements are met. Assuming you've got H. syriacus, it needs a warm, sheltered spot, preferably in front of a south facing wall, with well drained, but not dry, soil. Light soils will need some organic matter added before planting.
If you have met all those requirements, try top dressing the soil around the base of the plant next April with a little sulphate of potash, raked in.

thank you both for your advise. the garden gets a lot of wind. so thats probably the reason.have to put it somewhere warmer.