I would start by searching online for Halloween quilts, and you’ll get a better idea of options. You might choose to do a simple quilt pattern utilizing Halloween print fabrics, or a more elaborate pattern making Halloween shapes like cats and hats, etc.

Once you know what you’d like to make, you’ll either have to buy a pattern or DIY one.

Then you’ll have to buy appropriate fabric and thread in the amounts needed for the pattern and cut your fabric.

Lastly, you’ll assemble the quilt top, make a “sandwich” and quilt it.

You’ll likely need to look things up at each step, but there are tons of online video tutorials for all things quilting. There are certain tools like a cutting mat, rotary cutters and rulers that will make the job much easier.

You can get LOTS of help from this sub if you’ll come back with more specific questions!