import webpart to page layout in sharepoint

How can i add my own custom webparts to a page layout in sharepoint. i've exported the wepart and have a .webpart file.

i tried importing them in sharepoint designer without any success. I read a little on the AllUsersWebPart...but not really sure how this works

thanks

From stackoverflow

• try adding the code from the .webpart into the layout directly. (e.g. open in notepad copy-paste into SharePoint designer).

  Note: You should look up examples already in some layout pages as there are a few minor changes required to the webpart format (I vaguely recall).

  Be sure to version your layout pages as SharePoint designer can sometimes take liberties with your code and stuff the page up (and refuse to load/save it ever again). If this happens, use the web site to revert the page to a previous (working) version.