You've gotten great advice so far. When I put the quilt 'sandwich' together, I use my table and big binder clips to hold things in place. Put the backing wrong side up, smooth and clip down. Repeat with the batting and use the same clips 2 hold those 2 layers, then the top. If you don't have any safety pins, I would thread baste. Just take a regular sewing needle and normal sewing thread and run a line of large basting stitches in both directions through your quilt. I usually do basting about a hand-width apart in both directions. Check the instructions on your batting as to how closely it needs to be quilted. This will tell you how closely you need to tack. You could easily mark those spots with pieces of masking or painters tape. Make a mark on the tape, measure and put the piece of tape on the top of your quilt where you plan to tack. You'll end up with little pieces of tape all over the top. If you have another marking tool that you prefer, use that. There are a bazillion marking tools on the market. We've all spent countless dollars on find the one that we like best and works best for us. Just remember to test any pencils/pens on scrap piece of fabric to make sure your marks come out before using on your quilt.
Enjoy the process.