This is the original chair. I got it for around $10 in the store, and about $5 more or materials.
Start by removing all parts using a screwdriver in order to have the frame alone.
Here is how the frame looks alone. Naked.
Now it's time to paint it black using the can of spray paint. I didn't picture the process in order to avoid damage to my phone, but as you would expect is really fast and simple. Two layers of paint.
I got 2 meters or so of fabric, and decided to cover the cushion and back support. There's no need to remove the original cover, it's ok to put the new fabric on top. Easier and less mess.
After cutting the fabric to size, just staple the fabric. It's important to keep pulling the fabric as you staple in order to have a flat surface (wrinkle and bubble free) afterwards.
Cut the excess fabric.
The seat is now done.
Do the same thing with the back support
It gets a bit tricky given the odd shape if it. Remember to keep pulling while stapling.
Reassamble the chair.
This is how the finished product looks like