Step 1: Get Firefox
Congratz! You got Firefox. The first half is already finished- getting rid of popup ads.
What? No popups, just from installing a simple web browser?
YES! That's the beauty of it. But, you still see those ugly banner ads and even popups within the webpage. Below is instructables with and without the ads.
Step 2: Install Adblock Plus
So, it should have installed and asked you to restart Firefox. If you restart Firefox, it will keep the pages you were viewing and history and such. But, it needs some definition files to know what to block and work properly. This is covered in step 3.