Thanks DeathAndTaxes,

Well,, that was good explanation. So, if someone sends bitcoins to an address on a paper, then I need to enter that address in a bitcoin wallet in order to get the bitcoins associated with that address. Right?
In the bitcoin wallet (The PCs wallet application)
I cannot enter a new address by myself, all I can do is to make a label and the address is generated randomly. How can I enter the address on paper in the PCs bitcoin wallet application?