text size increasing and sidebar now belowbar

So, if you go to my little site, you will see these problems. It started with my trying to change the index.php to get a “next page” at the bottom of my home page. Which, altho they appeared, they did not work. Then, after trying to move my google ads higher on the sidebar, the sidebar moved below the text. Then, after I don’t even know what, the font size started increasing. Help! Obviously, I don’t know what I am doing. I went to the validation website and also took a lot off my sidebar, but I don’t think the errors that site discusses would cause what is happening. I also am not clear on the changes it is saying to make and some of it is old code that has been there awhile and not been dinked with. Does anyone have any answers for me, this low-tech site owner (and when answering pretend you are talking to a 2 year old child! ?? ) ? The site is https://letthedogin.com. It is a mess now. So sad.