I came across this one passage that I found amusing (maybe cause I was so wasted anything's funny) and I don't remember or care what page it was on;
it was something like "if you're giving money to the poor, don't let your left hand see what your right hand is doing"
Anyone care to explain this please? xD

Ahhhh yes I remember that verse. What it is basically saying is do not go to Church, put $50 in the church donation box and then BRAG about it to everyone IN ORDER TO get them to think that you are such a great guy or a wonderful person. It is saying that you should not seek PERSONAL GLORY because you should only do the things you do IN ORDER TO please God.

Do not worry about what anybody around you physically thinks of you. You should only worry about what God thinks of you. So yeah to summarise: Do not do things with the intention of gaining approval of other people around you, which is personal gain. Instead do the things you do with the intention of pleasing God.

Notice I didn't tell you to change your physical acts, putting $50 in the donation box is good don't get me wrong. Just think about WHY you are doing these things, for your own personal gain or to please God?

Ohh I get it
But what if I did it for "personal glory", but instead of bragging etc, I did it because I wanna be that "great guy" or "wonderful person" to be like helping out other people
What if I don't care or believe in a God, I just did it cause I wanna be a good guy?
You know like not seeking others' approval, but just that I know that I am is enough

When you give, remove yourself from the equation.

Ok maybe I worded my reply wrong (I'm like dead tired right now xD)
But I mean like if I'm not doing it for God, I'm doing it for me and whoever the donations are going to
Is it still wrong cause I'm doing it for me too?

That is a totally different thought than...

"if you're giving money to the poor, don't let your left hand see what your right hand is doing"

Either way...

This quote is right.

Your bible verse is talking about gaining fame and fortune from others. You are worried about what the world thinks of you.

However yeah, if you are not bragging about it then you aren't 'seeking approval from others.' That means that this verse is invalid to apply to that situation.