diff --git a/doc/lab03-silly_led/main.typ b/doc/lab03-silly_led/main.typ
index 0635c7f..2005f2d 100644
--- a/doc/lab03-silly_led/main.typ
+++ b/doc/lab03-silly_led/main.typ
@@ -1,3 +1,20 @@
 #import "/doc/metadata.typ": *
 
-= Linux System Programming
\ No newline at end of file
+= Linux System Programming
+
+// TODO
+
+This laboratory is focused on the user space. We make an application to change
+the blinking frequency of a led with button.
+
+It has some difficulties to locate the button on the GPIOs. Because this is not
+the same as we have done in the module in the precedent laboratory.
+-> explain
+
+Discover the epoll to trigg on file modification
+
+discover the timer_fd
+
+all is file
+
+all can be in the epoll to manage all event from files