Wash and dry a purchased t-shirt. Cut out a section from the Monkey fabric in whatever size you like.
Cut a piece of fusible web the same size as the applique, peel off the paper backing from one side of the web and press to the wrong side of the applique.
Peel off the paper backing from the applique.
Position applique on t-shirt and adhere using a steam iron.
Cut a piece of stabilizer a little larger than your applique and apply to the wrong side of the t-shirt.
Frame your applique with a satin stitch...or just straight stitch around the applique (like on the onesie) and it will fray a little after machine washing.
Peel off your stabilizer.
All done :-)