Oh sorry I thought I linked it! Yup, it's the pliers! This is what I got on Amazon.
https://www.amazon.com/dp/B079YN6WPF?ref=ppx_pop_mob_ap_share
I use stretcher bars. I got one set from Blick and another set from Artist & Craftsman Supply. Some sites sell bars individually or in pairs. So read the description carefully. Otherwise you'll end up with one long side and one short side.
I also purchased a canvas stretcher to help pull the canvas over the edges of the bars when I staple. This helps most especially if your canvas has very little allowance to go around the back of the bars. I didn't have one when I framed my first painting and my fingers were sore from all the pulling because the edges of the canvas were so short! 😤
To figure out what size bars you need, measure the size of the painting, not the whole canvas. You want to get bars that are about the dimensions of the painting. If you get longer bars, you'll have white/blank edges where you didn't paint, or you can always go over the white areas if it bothers you. Or you can leave it. Measure how much canvas you have to go around and the thickness or depth of the bars, too. You might not be able to staple at the back if your canvas edges are too short/bars too thick.
Maybe not necessary for small paintings but stretcher keys are also used to "tighten the canvas by expanding or opening the stretcher."
After stapling them to the bars, I just nail in some hooks and hang them on the wall. If you want to frame them, craftstores like Michael's or Joann's always have sales for the ready-to-use frames.
My first stretcher bars I bought from Blick, got the standard store brand ones for cheap. For the size that I needed, one individual bar was for less than $2. Delivery took about a week from East to West coast though. Used thumbtacks to attach the canvas but I had such a hard time because there was very little allowance on the canvas to stretch it over the bars. My fingers were sore from all the pulling.
My second set of stretcher bars I purchased from Artist & Craftsman Supply just because they had the sizes that I needed. Also learning from the first experience, I purchased a canvas stretcher from Amazon and oh boy, it made things so much easier, also used a staple gun that time. I was very pleased with how the finished product turned out.