Input{xxx} : file not found

I’m using TexMaker and MikTex, and I created a folder called "first" where i put the .tex file and another file called xxx.txt. Now I want to import the file into latex by saying input{xxx} and everytime and error occures saying: xxx.tex not found. I tryed with TexEditor and the same problem occures. Shouldn’t it be xxx.txt not found? How can I manage with this error?