Welcome to subsim, Mike
You say you can't find the radio? If you aren't using any of the mods that change what your orders bar looks like, you can click on the radar station tab and then click the button that looks like a radio. If you hover your mouse over the button, a tooltip should appear that says "Activate radio" or something to that effect. When you click on the button a graphic of a radio appears. On it are buttons to turn the radio on, off and to go up or down the frequency dial. Click the on button, then just hover your pointer over an empty area on the radio and it will tell you what frequency you are on (probably 20 to start with). Then click the up or down buttons to get to the frequency that you want.
If you're going to do much in the way of adding radio stations to your game, consider installing the radio station manager (link in my signature). It will make adding and using radio stations much easier as well as handle the "same old news" bug that happens when you load a game saved while at sea and allow you to correct any problems with radio stations that can cause CTDs.
Don't forget to check out the other fine radio station mods (take a look in the list of mods stickied at the top of the forum).