I am often confused while speaking the sentences like
I explained to you the reason
I explained you the reason.
I told you (Or, I told to you)
There are many such instances where i do not know whether to use " to " or not.
Kindly help me learn
Unfortunately, there is no rule. You have to learn each verb and whether or not it goes with "to".
I tell you every day that I like you.
I say "I like you" to you every day.
I suggest [that] you wash your hands.
I suggest to you that you wash your hands.
I regularly explain to him what I do at work.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.