You can download and use any FTP client you like. I'm using SmartFTP so that is what my instructions are for. Anyone using another client and they would like to create instructions for that let me know and I'll pin it.

You can dowload a copy here, it's free for private use and no nag screen until you used it for 30 days http://www.smartftp.com/

With the new FTP client installed you have to access your account on the astahost.com server. If you are using a subdomain the FTP address will be ftp."yoursubdomain".astahost.com (Replace everything between the " ") The image is from trap17 but everything else is the same.
next is your cPanel username (this is for the main FTP account) and last your cPanel password.
Middle part is the files and folders you should see for the default setup.
Third field down you see connection messages including login errors

Uploading your website to the "public_html" folder. Make sure you remove the "index.html" file that is in the "root" directory of your account and replace it with your own "index.html" file (homepage)

The files will show in the www folder instantly and you can access your website as soon as you removed the default "index.html" file from root.