| measure from the fold 1/2 the desired width of the bottom plus 1/4" | 
| measure the same distance from the SEAM line | 
| cut along markings.  It will be a square from the  seam line (not the edge) to the fold  | 
Now, match the FOLD to the SEAM. Stitch. This will create a square bottom. A 1" square will create a 2" wide bottom. 
| Finished right side of flat bottom | 
Hope this works for ya!!! 
Keep stitchin', Marsha