Update.md

@@ -8,7 +8,13 @@ Before update you should be warned that there is a good news and a bad news
 
 ## Update
 
-In order to update, go into openfpm_pdata project and do
+If you previously installed OpenFPM you will have 3 folders
+
+* OpenFPM dependencies folder, is the folder that you gave to the install script with -i option /install -i "/OpenFPM/dependencies/dir"
+* OpenFPM installation folder, is the folder that you gave to the install script with -c "--prefix=/OpenFPM/installation/dir"
+* OpenFPM source folder, is the folder where you cloned the code
+
+In order to update, go into openfpm_pdata project source file and do
 
 ```bash
 git pull origin master