I made this bandanna tablecloth for our July 4th barbecue, but I think it would work fine for all summertime barbecues. I followed the instructions found on Martha Stewart's website. (I apologize for my photography, I'm a not-so-great photographer using a not-so-great camera).
2. Pin bandannas right sides together to create the width (3 across, in my case. The bandannas are rectangle, so I pinned mine long sides together for the width). You want to match the bandanna pattern lines rather than the edges of the bandanna (if you hold the bandannas up to the light you can see the pattern lines, making it easy to match).
3. Machine-stitch just outside of the pattern line so that when opened the pattern line of each bandanna is almost flush with the other. Iron the seams flat.
4. Sew however many across-wise strips you'll need, then sew these strips together to form your tablecloth.
5. At this point, Martha sewed a hem. In the interest of time, I just left mine with the existing hem from the bandannas. I may go back and sew a hem later because bandanna hems have a tendency to come undone over time.
If my instructions have confused more than helped, please refer to Martha's instructions :0)