Women can use breast pumps for various reasons. One could be that you have twins or multiples and need to feed to babies at the same time. The having a bottle of breast milk ready is a good thing. Other reasons can be that you are away during certain times of the day and your spouse will take of the baby then. The last reason is that you might lactate too much and need to pump out excess milk.
A breast pump is comfortable for women to use. It enables you to store milk in the fridge and feed the baby later. It also releases pressure from your breast if you lactate a lot. Even if it seems strange to use a pump to extract milk, there are only good reasons for it.
Of course, buying a breast pump might not be the best option. Ask your hospital or local pharmacy if they have pumps for rent or even for you to borrow for free. Pumps come with disposable funnels, so you do not have to be afraid that they are filthy and unsafe. They are always sterilized before you get to use the pump.
Your attending midwife or pharmacist can also guide you when you choose what kind of breast pump you need. There are manual and electric ones in the market, and they come, of course, in different sizes. Get one that fits and that you feel comfortable with. There are even pumps that can access both breasts at the same time; but these are only necessary if you lactate a lot. On the other hand they will save you time and stimulate the lactation process even more.
Once you have acquired a breast pump you need to be sure to clean if every day in order to prevent bacteria from starting spreading within it.
In order to get the breast pumping process to start you should have clean hands. Make sure that they are warm to. Touch your nipple to start the lactating process and grab the nipple between your fingers. Push it gently towards your body (inwards, so to say) and the milk will slowly come out.
Last but not least, remember that there is no breast pump in the world that is as efficient as your baby.