A tutorial for beginners to patchwork: How to Piece Patchwork.
Cotton fabric generally has 2 sides, the right side and the wrong side. The right side is The side where the pattern is brightest:
For solid colour difference is much harder, if not impossible, to see. My motto is 'can't see it, don't care'!
Place one of the squares on top of the other one, right sides together:
Match the edges all around the square and pin, perpendicular to the edge that you are going to join:
Your sewing machine should sew over the pins, if the pin heads are placed on the inside of the block.
Using a 1/4" patchwork foot you will sew along this seam.
A patchwork foot has a metal guide on the right hand side that allows you to line the fabric up against it to give you the perfect 1/4" seam.
Sew this seam, ensuring that the fabric is lined up with the 1/4" guide, remembering to back stitch at the beginning and end:
Back stitching ensures that your stitching won't come apart, so make sure you always back stitch.
Once the 2 blocks are sewn together, the seam needs pressing. You will need a really hot iron.
I prefer to press the seam open, but you can press them towards the darker fabric - experiment and decide which way you prefer.
First spread the seam with your fingers:
Then use the iron to flatten the seam completely:
Turn the piece over and iron the other side too.
I hope this helps you on your patchwork journey!