How can i decompose my signal into five parts using daubechies wavelet(db4) ?

I have an EEG signal which i had implemented in matlab and then added noise to it. Now i need to filter the noise out using wavelet transform. Can any one please help me ? This is my code:

1. fs = 512
2. T = 1/fs;
3. N =length(EEGsig); ls = size(EEGsig);
4. tx =[0:length(EEGsig)-1]/fs;
5. fx = fs*(0:N/2-1)/N;
6. x= EEGsig;
7. sd = 0.1;
8. normal_noise = sd*randn(1, N);
9. noisy_EEGsig = x + normal_noise;
10. figure();
11. subplot(4,1,1);
12. grid on;
14. plot(tx, x);
15. xlabel('Time [s]');
16. ylabel('Amplitude');
17. title('Original signal');
18. subplot(4,1,2);
19. grid on;
20. plot(tx,normal_noise);
21. xlabel('Time [s]');
22. ylabel('Amplitude');
23. title('Noise');
24. subplot(4,1,3);
25. grid on;
26. plot(tx, noisy_EEGsig);
27. xlabel('Time [s]');
28. ylabel('Amplitude');
29. title('Original signal + Noise');