How can I use a beam profile in ASCII format?

Dear fluka experts. I am just starting out with fluka. I have a beam profile in ASCII format and how should I add it to fluka? I would appreciate it if you could show me a source. Your answer is important to me. Thank you very much.

Dear @Semina,

Please, have a look at the source routine lecture from the last advanced course, particularly at slide 19, and at this post on the forum.