I'm not really qualified to give an accurate answer but from my point of view, "here" and "over here" have similar meaning. Except that "over here" is more used ton indicate a direction rather than an exact location unlike "here". Also, "over here" is what we call a 'phrasal verb'. Phrasal verbs are an important part of the English language and often the use of a phrasal verb is better than use the verb alone though there is no grammatical nor meaning difference. Just the way "my father's sister" sounds more natural than "the sister of my father". You'll need to identify when use phrasal verb but there is absolutely no rule for that. Here is a website to find the meaning of phrasal verb (which by the way could be completely different from the verb itself) http://www.usingenglish.com/reference/phrasal-verbs/

I looked for over here & the meaning is the same ,"here".

Thank you. I understood better now.

"Over here" is commonly used when giving a command; it suggests that something is going to move toward the speaker: 1. Bring that box over here. 2. Tell him to walk over here. 3. Your room is over here. "Here" itself is less dynamic and usually used to indicate that something or someone is physically present: 1. Where is your son? - My son is here (in the room). 2. The bus is here. 3. My car is not here.