I got an old oscilliscope from a junkyard for $5.  It's all tube and everything seems to light up.  However, I don't know how to go about plugging something in to get a wave going.  Any help would be much appreciated.

Well you should at least be able to get a flat line across  the screen (more than one line if its multi channel) which you should be able to move up and down and left and right using the controls. You will need an oscilloscope probe to get a signal on it, good ones are pricey, but you can make your own from a BNC plug a lenght of 75ohm cable a crocodile clip and an empty ballpoint pen.
There should be a point somewhere on the case with "probe cal" or "calibrate" or something on it, you can connect it to the input and you should get a square wave at 1mS/DIV.
hope that makes some sense?

Can you give a model and make? That should make it easier.

One thing to keep in mind with ANY old tube equipment is that it will almost certainly need a cap job. If it doesn't work, it possible that replacing the caps may bring it back to life.

If you don't have a trace on the screen, try looking for something that talks about "triggering". Most scopes have an option to trigger the sweep off the AC mains. That should at least get you a horizontal line.

Take care,
-Peter

Sure it's a Tektronix Type 504 Oscilliscope

Here's the manual for you.

http://64.7.66.217/circuits/tek504.v6.pdf

Better grab it soon as I'll be getting rid of my T1 line in two weeks and the address will go away.

In that 80 page, 17.1Meg PDF file is the schematic with lots of repair info too like test points and voltages. One of the cool things about Tek stuff is that it was made to be repaired.

If you jumper between the input and the "cal out" jacks you should be able to observe a square wave. Do you get any sweep on the display? Try playing with the triggering. If you set it to "line" it should show you at least something on the screen.

What a score for $5!

Best of luck!
-Peter