I want to start trading in Bitcoin to dollar,
but I looking for someone sends me mesages
every day tells me it's time to buy and it's time to sell.
Where can I find this person? 
The person you are looking for is that person you see every in the mirror. Yes that is right yourself.. take some time and s do some studies 90% of the people around here are for self interest ..
but if you do some studies by your self you will;be better off at that point even if you want to take external advice you would be able to judge for yourself.