when one make so that his right hand knows not what the other does, he just avoids obstentation, which is a great danger. When the Lord said that, He was referring to those scribes and pharises who used to practice a more apparent and outlooking religion rather than an inner and spiritual one, to be seen by the people, and be good in the eyes of men (but not of God).
Now, when we are among the people, for example on street, and we have to give alms onto the poor, we can do it also if there are 10000000 people, and this is because what really matters is the way you do, and not who is watching you when you do the good deed. What matters is that your heart may be clean and clear, not double faced unto God.
Naturally, whereever you are, wether in the desert or at the national stadium, you must help the poor.
Furthermore, remember that "you are the salt of the earth; without salt, how shall the earth taste be?" and "you are the light of the world; and the lighted up lamp cannot be put hidden under the bed, but must be put on the roof of the house , so that every one might receive light from it". So, you must shine with your deeds unto the gentiles, to make them glorify the Father; but not with by obstentation, just by kindness and semplicity, giving the example.
Shine your (HIS) Light from the top of the house, and let all His enemies bow unto Him.
Sebat le Qeddest Selassie!