How to get transfer pictures from my computer to my iphone?

I have a lot of pictures on my windows 8 laptop and I want to put them on my iphone but I keep trying and all it keeps doing is saying import, but i don't want to import my pictures that I have on my phone, I want to put some of my pictures from my computer to my phone, please please help

ITunes

1. Plug your iPhone into your computer, open the iPhone folder go into pictures and all your photos are going to be there. Then minimize that on half the screen, open the photos in your library on your computer and minimize it to the other half if your screen. You can either drag on pic from you computer library to your iPhone library; or you can right click on the photo you want, click copy, then place the cursor on the iPhone library and right click again, and click paste.
2. Or you can make a folder on your computer, then add your photos into this folder, plug in iPhone, open iTunes and set the photo destination to the photo folder. And then sync your iPhone with iTunes, Done.
3. You can also use a 3rd party software like this iPhone file manager, it can help you upload photos, songs, videos, contacts, files from computer to iPhone easily.