I'll take a stab at it. Please don't take this the wrong way but you might not be ready for a compressor or you might not be certain of the benefits due to the way you talk about "hearing" the compression. You really should not hear compression so much as feel it. Yeah, sometimes, people use it as an effect like guitarists into chicken pickin but it really is not a tone shaping device, especially for bass. You also mention that you were striking one string repeatedly. If the release is slow, it won't have any time to recover and the compression will stay on. Everyone has their own preferences for attack and release and it can depend on how fast you're playing and how fast or slow the compressor circuit is. I tend to like a slow attack to not lose the initial impact and then a faster release.
First, I'd avoid EH for compressors.
Compression is pretty much always used on bass in recording and mastering. It's not used nearly as often live but it does have its uses. Some use it to limit peaks to keep amps from distorting to protect drivers. Some use it to mask or correct for inconsistent playing levels or to sweeten or thicken the tone. I'll assume that is your most likely goal. The Fender Bassman compressor is a fine choice in that price category though it is on the more subtle side compared to many which can be a good thing to keep you out of trouble. It only goes up to 8:1 so no heavy limiting. It's also a soft-knee so it's not as aggressive as something like a Keeley Bassist which uses a similar circuit but is hard-knee. Since you have access to playing that one, I'll do my best. It's a bit quirky in that the knob labeled Blend is not what most Blend knobs on a compressor do. Rather than blend between dry and wet, it's really just a dry or clean volume that you use to blend in with the compressed level. To start with, I'd turn the blend down. Set the release switch down for fast release. If a pedal does not have a blend, I'll typically set ratio to 4:1. When it comes to setting ratio when I have a blend option, I might go higher like 8:1 so try setting that switch to Up at first. To set the threshold or input level, labeled Comp on this one, make use of the LED. I usually play a loud note like popping the open G-string (keep it cool) and adjusting the level until it turns occasionally red on the peaks. Now, while popping the open G, adjust the Output level knob, turning the pedal on and off until the volume levels are the same. Finally, you can add in some clean signal with the blend knob but don't overpower the compressed signal as unity gain on this knob is about 7 so I'd keep it there or under. Now, when you play normally, it should feel a little fuller and thicker. The loudest notes will be no louder than without the compressor on but the quieter ones will be louder. Try this to see if you like what it does: Play the notes of a chord: root, 5th and octave, one at a time, without muting any of them while playing. Do this with pedal on and off. Do you hear the notes as more even with it on? Chords should sound much nicer without having weaker notes disappearing.
Oh, if you're using overdrive and distortion pedals, they inherently compress so you should not need a compressor on with those.
