Client/Server Side.

Hello how can i run/import serverside scripts inside client side?

Yes i tryed
[lua]
if SERVER then

end
[/lua]

AddCSLuaFile("")

But how can i so run it then you click on a button?

You can’t really use a client-side only code at a server-side script and Vice Versa, however, if the function is shared, it works for both server-side and client-side.
To send data from the server to the client you can use usermessages.