Made the pattern? Check.  Cut it out?  Check.  Time to sew your tank top!

Use seam allowances that you added to your clone pattern (most home sewers use 1.5 cm, I like 1 cm.)  Use the stretch stitch on your sewing machine.  (Can't find a stretch stitch?  Use a small zig-zag instead. Got an overlocker?  Lucky you, use it for all the steps except top-stitching.)