I can't seem to learn css box model and positioning

Okay, so I have read lots of online tutorials, watched youtube videos, even took some courses but I just can't seem to get past the css box model and positioning or at-least be able to use it to my advantage by building web layouts with it, even the very basic ones. I understand HTML really well but when it comes to positioning elements to create layouts I get completely lost. It's getting really frustrating.

Navigation help for class

Hi, guys! I'm really new to the CSS world, and I have class website due on Monday. I realize it's short notice, but I'm pulling my hair out here.
Okay, so. I need to have a horizontal navigation bar with a transitional element. I've figured this out. What I can't figure out is how to make a vertical drop down menu from one ("Profiles") link/list item in the horizontal menu.

Tumblr Help PLEASE

Hi. I'm using a theme on tumblr that someone else made. Originally, the description box was right above the next button on my sidebar, but I tried to move it, and I don't even know what I did, but now it's slightly to the left of where it was. I'd like to move the description box into the upper left corner of my sidebar, and I'd like the next button to be right below that. I'm not sure where in the html coding to do that, or what to do. (I have almost no idea what I'm doing) Could someone please help? You can see what my blog currently looks like with the html coding as it is right now at katnisskid.tumblr.com

Here is the html coding that I'm currently using:

Internet Explorer fix? Elements are overlapping.

Hello!

I'm new to the forum and relatively new to web development. I would be very grateful for some assistance with a website I've been working on: http://www.jameskimballdds.com

The website works with no problems in Firefox, Safari, and Chrome. However, in Internet Explorer, it's not showing up correctly. Elements are overlapping and the slideshow is not working.

Exclude a CSS rule defined on an HTML tag

Hi all,

div { font-size:14px; font-family:Times New Roman; position:relative; float:left; }

That is a css rule applied in a page that I need to work. I have no control over altering that. Now I need to put a div element in the page to which those rules should NOT apply. How do I do that? Any help is greatly appreciated.

Thanks in advance,

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