there is a setting in the admin that you can specify number of posts shown on homepage, you can set it to 1, and only display a "welcome" post, or you can delete the 'post loop' in your index.main.php file and enter your welcome message manually while you are at it...

About the 404, you have chosen to use "pretty urls", most likely; you dont have apache mod_rewrite enabled, ask your hosting provider about it.. and try renaming the file sample-htaccess.txt to .htaccess in your root folder, that might help.

Thanks for your reply. I'm so new to this though, I don't know how to access my root folder. My host provider is Host Gator and from the little I've dealt with their customer service, I'd be best off trying everything else before asking them about anything. One of the people I talked to there told me that Wordpress doesn't accept HTML...they don't seem to know anything about the actual blogs, just their service.

get a decent ftp software, maybe a free one like 'filezilla' and connect to your webfolder using the credentials given to you

Renaming sample-htaccess.txt didn't work. My control panel has Apache Handler, but I don't know if that can do what Apache mod_rewrite would do.
I can install filezilla but I don't know how that would solve the problem of my page errors because I don't know nearly enough about websites to do that.