I myself

I would like to know the meaning of "I myself".

I will also ~~

This is a subset of various constructions in which a reflexive pronoun corresponding to the subject is placed someplace in the clause in question after the subject to indicate a number of things. This can indicate that the clause is with respect to the case of the subject and or that the agent of the action in question is only the subject. Furthermore, it can give the clause a general emphatic tone overall. Also note that when actually spoken, said reflexive pronoun is usually intonated and stressed on the "self" so that it is distinct from the rest of the clause.

Note though that the most common place where said reflexive pronoun is placed is at the end of the clause, not right after the subject. Also note that it may show up in other places, such as right after the finite verb but not at the end of the clause, too.