Jump Physics, Codes

Hello everybody,

Please help me with a jump function to my char.

im creating a side scroller game, platform game.

but i dont know how to fix this.

ralph_spoon@yahoo.com

thats my email,
please help me. i know how gravity works, but the jump code.(im stupid in this thing)

what happen is when im in another boundary, i cant jump anymore.

if(heroMale.y < boundaries.y)
{
jump = false;
}

if(heroMale.y > boundaries.y)
{
jump = false;
}

thhanks in advance !!!

cheers,
raphaelle