I don't know how to do the tutorials I see some using - theirs are very professional and this one isn't. Hopefully, however, this shows you how to do this.
Take 4 fat quarters, or comparable fabric pieces. Choose fabrics that you think go well together. I cut mine to approx. 17" x 21".
Stack them up and make 2 horizontal cuts (in the whole stack) and 2 vertical cuts. It is more interesting if they are not parallel.
Shuffle the stacks so that each of the 4 different fabrics are represented in what will become a completed placemat. Try not to put the same fabric next to each other - in other words you have 9 pieces among the 4 fabrics.
Now reassemble the whole thing. Because you are taking out 1/4" seams, it will not perfectly line up. Don't worry! This one really 'bad' one is about 1/4" off (horizontally) but you don't have to worry. This next one is quite close to aligning.
When the 9 pieces have been reassembled into a whole, press like mad. Press the back and from the front. Place the reassembled whole on top of a piece of batting. Along each seam line, stitch through the top and the batting. You can use decorative stitches or here I used just a plain zig-zag. I would suggest you avoid stitches that are really thread heavy - open, airy stitches seem to work well. A wavy line is very attractive.
Your eyes will follow the line of the stitching and will not see those places where the seams do not align.
Make the back by laying a piece of fabric right side down on top of the stitched top. Stitch around, leaving an opening to turn it right side out. Trim seams, cut your corners, turn it right side out. Slip stitch the opening closed - I do this by hand. Press, press, press. Top stitch approx. 1/2" from the edges.
Do let me know if you have questions or if I have not been clear. Good luck. These are fun and easy to do. You can be most creative - copy the colors of someone's dinnerware or the colors of their dining room, maybe reflect their hobbies or interests. Go for it!