Pro advice
Unfortunately you have been given a lot of inaccurate information. As a professional for over 40 years and a believer in keep it simple, here is what you need to do.
No tripod - the flash alone should expose the image
100 ISO
125 / sec, or the highest sync speed the camera allows
Ambient (room) light high or low - no matter - the flash is the only exposure
Bounce off ceiling aimed slightly behind you
The folds in the muslin will show. Consider photographic paper roll, probably cheaper than muslin anyway.
Can be made white in Photoshop or Photoshop Elements by placing the magic wand in the area and feather to about 3. Keep clicking in the background whilst holding down "shift" adding to the selection till the entire muslin is selected.
Then select Enhance > adjust lighting > Levels. In levels you will see a white eye dropper. Click that in the darkest area of the muslin. The entire muslin will be perfectly white in a moment.
All of the above works, but is not as professional as using a camera with external flash socket and obtaining a two flash semi-pro system
As the electronics are very delicate in modern cameras, all external flash unit systems should be triggered by an external wireless unit. Mine was about $20. Saves tripping over flash cables too.
When you have a 2 flash system, bounce one off the roof slightly behind you (or via an umbrella or bounce off a card or muslin near your camera, slightly behind - to avoid light spill into the lens) and the other flash aimed at the background, say sitting on a tripod near floor level. Or simply sitting on the floor with the reflector on cooking foil to bounce it up and to keep the floor from any heat from the flash.
If the rear light does not spread enough, either move it away from the background or cover it with an opaque white plastic shopping bag. Do you still have thin white shopping bags in your area? That's all I use.
You can also have a coloured background by placing colour cellophane over the rear flash.
Alternative
Do you have a big window in the house? On holidays I take some outstanding images just using the light near the window in the hotel. See attached. ( note I did a quick change of background to white - you would need to enlarge your photo and do more of the hair areas than I did)
Set on Auto, spot meter reading - easy as.