diff --git a/B-mass-model.md b/B-mass-model.md
index 48c7e3d..63ad66c 100644
--- a/B-mass-model.md
+++ b/B-mass-model.md
@@ -40,14 +40,19 @@ Standard RooFit does not include a double crystal ball or ExpGaus function used
 
 ### RooDoubleCB compilation
 
-Run `build.C` in `Code/RooFit/RooDoubleCB/`
-
-**TODO** try this out!
+Run 
+```
+cd Code/Selection/RooFit/RooDoubleCB/
+root
+.L RooDoubleCB.cpp+
+.q
+```
+If you do not compile the RooDoubleCB before running the MassFit for the first time, the code will compile but later throw an error it cannot find  macro ./RooFit/RooDoubleCB/RooDoubleCB_cpp.so.
 
 ### RooExpAndGauss compilation
 
 ```
-cd Code/RooFit/RooExpAndGauss/
+cd Code/Selection/RooFit/RooExpAndGauss/
 make 
 ```