Unless you need to do some fancy loading of modules, you do not need to do anything to modprobe.conf. As is, modprobe will load a kernel module, if the module is in /lib/modules/
I have used it to load sound modules, parallel port driver etc. All I have done is, as root, 'modprobe nameofmoduletoload'. Success is indicated by no messages. If it doesn't work, you will get messages, often very cryptic on the screen. dmesg is another source for error information.
I have never done any harm to any of my systems by using modprobe, so have a go at it and see what happens.