a little direction please

Hello all.

Well is what im wanting to do is attempt to write a program in C# that take a .txt doc and add your desired string or character at the beginning or end or both. I have no idea where to even start so I was hoping someone could shed some light on this for me.

Also while im at it, is it possible to take 2 separate .txt docs..lets say one is filled with the names of documents and the other is filled with links to the document, can you join them together, while placing lets say html or css(doesn't matter just string in general) code/tags at the beggining of the line, in between the title's and links of the documents and at the end also?

thanks in advance for any input