There are many free WordPress themes available on many websites, I like to use www.wpthemesfree.com and sometimes http://wordpress.org/extend/themes/ as both of these are 100% free themes. You can even use the google search above and type in wordpress themes, wordpress themplates, free wordpress templates, or even free wordpress themes and find tons of other websites for wordpress themes. Some other websites will give you generic themes free and offer nice looking themes that you have to pay for. I recommend just using the free wordpress themes.
A theme or template is what your wordpress blog will look like. Themes are your blog's design, where everything is located, etc. Most wordpress themes you can customize as well, change your wordpress theme's layout to fit your blog's needs. You can even create your own wordpress theme as well for free.
To install a wordpress theme is not too difficult, below I will go over the steps in installing a wordpress theme. There are a few different methods to installing a wordpress theme, I will be going over various methods to install a theme, but for now I just have the method that everyone can use no matter what webhosting company they are using to host their wordpress blog.
Download FileZilla FREE which will allow you to upload this theme to your webhost|server. Make sure you download the client version, not the server version.
Install 7-Zip and FileZilla - Basically click next, next, etc.
Now use 7-Zip to extract the wordpress theme folder from the theme_file.zip, I think right clicking on the wp theme file and going to Extract should work.
Now use FileZilla to connect to your webhost|server
Enter domain name, username, and password. (This user/pass is for your webhost, not WordPress blog).
After you are connected navigate on left side to the wp theme folder
Navigate the right side to /public_html/wp-content/themes/
Now on the left side, right click on your wp theme folder not the *.zip and click Upload
After transfer is complete you may disconnect and close FileZilla
Now open Firefox, Internet Explorer, Safari, or Opera
Type in the address bar domain.com/wp-admin/ replacing domain.com with your domain name
Type in your Username and Password, click Login
Now you can go under Appearance on the left side.
A submenu will appear click on Themes
Below this click on the Thumbnail Picture of the blog theme you want to make active
Now on the top right of this window, click Activate Theme
Download the wordpress theme you want to use. DO NOT extract it like we would with FTP, we are going to upload the *.zip file itself.
Login to your cPanel you can do this usually by going to your webhost's website and login like www.bluehost.com or you can also go to http://yourdomain.com:2082 which will ask you for your user/pass, this is your webhost username and password, not your wordpress username and password.
Now that you are logged into your cPanel, scroll down and find "File Section". In this section you will see "File Manager". Click on "File Manager".
Now navigate to your website's theme folder, which is in wp-content/theme/ of the root directory which would probably be /public_html/wp-content/theme/ to open folders here, you have to double click the folder itself, not the names.
After you get to the theme folder, on the top left click "Upload". This will open a screen with a few boxes to type in and a "Browse Button" on the right.
Click on "Browse" then tell it where this file is located on your computer. It will start uploading.
When it is done uploading go back to the File Manager where we were, and you will see the new theme here. Click in the box infront of it to place a checkmark next to it.
Now click the "Extract" button at the top right hand side. This will extract all of the files out of the *.zip file and make them a standard folder.
Check mark the theme again, the *.zip file, and click delete, we don't need this anymore now that we extrated the standard folder out of it.
Login to you wordpress blog, http://domain.com/wp-admin/
Click "Appearance"
Click the thumbnail of the theme you want to activate.
Click "Activate this Theme" in the top right corner of the preview.
Done
I hope these guides to installing a wordpress blog theme has helped you. If you have any questions about installing a wordpress theme you can ask them on my Online Business Help Forum.