How would i go about making my block do something on a random tick.

For example spawn in an item

setTickRandomly(true);

@Override
public void updateTick(World world, args)
{
if(!world.isRemote)
world.spawnEntityInWorld(new EntityItem(...));
}

the wiki says this

@Override
public void updateTick(World world, int x, int y, int z, Random random) {
    if (world.getBlockMetadata(x, y, z) == 1) {
        return;
    }

    if (world.getBlockLightValue(x, y + 1, z) < 9) {
        return;
    }

    if (random.nextInt(isFertile(world, x, y - 1, z) ? 12 : 25) != 0) {
        return;
    }

    world.setBlockMetadata(x, y, z, 1);
}

This is entirely dependant on what you want to do with the random tick. In the example you gave it does some plant-like behaviours. But you want to spawn an item in, and that doesn't need the code you've just posted, GotoLink's code is what you need.