The method used for the implantation and positioning of your implant depends on your anatomy and the recommendations of your plastic surgeon. 
The incision can be positioned either in the inframammary fold, where the breast meets the breast wall, around or through the areola or in the armpit.
Wherever the incision is made in your case, your surgeon will always try to position the scar as unobtrusively as possible.
Through the site selected for the incision, your surgeon will lift the breast tissue and skin in order to form a pocket for the implant either immediately behind the mammary gland or behind the large breast muscle (pectoralis muscle). The implant will then be positioned in this pocket.
Thanks to today’s modern techniques of minimally invasive endoscopic surgery, the incision can be very small and the pocket for the implant can be prepared endoscopically with precision and with minimal bleeding. This technique on the one hand reduces the risks of the operation and on the other hand improves the surgical results.  
Ask your surgeon which incision and techniques are preferable in your case.
Drains are positioned in the implant pocket and left in place for about 12 - 24 hours to drain off any blood and wound fluid. Finally the breasts are bandaged to reduce swelling.