I've been Playing about an hour and located my first weapon mod. It has the same name as a gun I am carrying. Trouble is, how do I attach it to the gun? There does not appear to be any option on the reload or work benches, and the help menus don't explain it. I'm either an idiot or I missed something, or both! Help?

Use your Pip-boy, and with the weapon you wish to attach the mod to press LB then select your mod. (Depending on what system your on the button will be different, but the basic part of it remains the same)

same place on pip boy screen (top right) were it asks you to repair/maintain ur items it comes up under there

It took me a while to figure this out too. I was trying to find repair benches and reloading tables and than I just happened to notice it in my pip-boy.

In the pip boy, X marks the mod spot. (If I'm remembering right).

Yes for the PC select the weapon in your Pipboy then hit the X key.

It will bring up a list of available mods for that weapon.