So this is WordPress.. I guess the FTP bit will be confusing to ppl who never use it.
This is how I install themes:
1. browse and download the themes from here
2. unzip the themes
3. u need to have an FTP client/program to make it easier to transfer the theme files. there are free softwares out there, maybe googling using “free ftp client” will lead you somewhere, i use the trial version of AceFTP 3. u can also check download.com
or alternatively you can use the “hard” way by clicking start -> accesories -> command prompt and then type ftp yoursite.focuser.net
4. using ur fav ftp client, just transfer the theme folders to your wp-content/themes
5. login to your admin site, and activate the theme (under presentation tab)