[jv_map]

if(condition)
{
// <-- execute this if true (condition is 1)
}
else // optional
{
// <-- execute this if false (condition is 0)
}

example
[code:fad00]
if($player.health < 50)
{
$player iprint "ouch!"
}
[/code:fad00]
In this example you don't strictly need the curly braces as there's just one line below the if.