Need more help understanding how to use Fade In /Fade Out

[vinckles]

Hello,
          I have scoured the internet and youtube for days trying to learn the secret of how to use the Fade In / Fade Out feature on Avidemux.
    Nothing is clear cut obvious.
I merely want to add a 1/4 second fade to a piece of video, about 1 min long.  I require a fast fade at the start and one at the end. ( Longer fades look awful, from what I have seen on youtubes.)
     I have no idea how to do it:   Is it a case of:  Pause the video at the point you want the first frame to turn black, then type 125 ms into the "Start Time" box  to make the Fade In?  Don't know what comes next?!
     Don't know what to do next to make the Fade Out...?    My 1 min clip is not complete in itself. There is a second or so of unwanted material before and after the points I want the fades to take place.
     Can anyone be persuaded to make a lengthy youtube with audio, step by step, explanation, please?
      I also have Xmedia Recode Video Converter, version 3217.  I thought the Fades on that would be easy but they too are impossible...  I always get a black screen all the way.    Fade In /Fade Out is obviously a very complicated science with video equipment!

[Jan Gruuthuse]

You need to enter the times manually. [hours]: [minutes]: [seconds], [milliseconds]
Filter: Fade to black

Start time: where fade begins
End time: where fade ends

Fade type:
[Out] ends on black
[In] starts on black

right hand bottom on avidemux canvas, mark
[V] Play filtered

You should see the effect immediately.

Youtube : Fade to black Filter, How to
below video click show more.
do note the filter was applied twice in & out, one after the other.