Cannot run cuda on ubuntu 22.04.1

hello,
I am trying to run via termianl a simple program:

include <stdio.h>
__global__ void hello_world_kernel()
{
    printf("Hello GPU World!\n");
}

int main()
{
    hello_world_kernel <<<1,8>>>();
    cudaDeviceReset();
}

but getting always :
nvcc testme.cu -o hello_gpu
./testme.cu
and it’s outputing always:
./testme.cu: line 3: syntax error near unexpected token (' ./testme.cu: line 3: global void hello_world_kernel()’

nvcc --version

nvcc: NVIDIA (R) Cuda compiler driver

Copyright (c) 2005-2021 NVIDIA Corporation

Built on Fri_Dec_17_18:16:03_PST_2021

Cuda compilation tools, release 11.6, V11.6.55

Build cuda_11.6.r11.6/compiler.30794723_0

from nvidia-smi:
NVIDIA-SMI 510.108.03 Driver Version: 510.108.03 CUDA Version: 11.6
I am using conda, I have installed successfully the cuda, because I can run in GPU the tensorflow