easiest way to integrate own functions on startup

Hi,

I am currently writing some own functions that I frequently need.

So, it would be perfect if I could load these functions at the  
beginning of each R-session with a small command.


I tried to generate a R-package and install it that way.

But it seems that it is not so easy to add new functions to an  
existing R-package.
So I am not so flexible by that.


Is there a way to just load an .R-file which contains the function- 
definitions with a small command?
So that the functions are useable in the current session?


I tried load() but I get an error message...