Simple but I foget

Yeah, this is a really easy question that I knew how to do buuuuuuuut I forgot. Basically I want to run a program multiple times on visual studio.net 2003, and read two bits of information to a file and transfer it to excel. Whenever I try to read multiple information to just add on to it, it just keeps over-writing the first information I put there and it annoys me. Any help? Thanks.