If you have uploaded all the PowerStore files and folders to your remote hosted website, you should be able to get to your site and begin setting up powerstore by typing
index.php into the address bar of your browser. (change 'yoursite.com' to your own domain name).
If you uploaded the whole PowerStore300 folder then the address you would type in would be:
How did you upload your files to your site? When you first buy hosting space from your hosting provider they usually send you your ftp details, - ftp address, password, username and host directory. It might help you if you had this.
See if you can now access your PowerStore files and let us know what you get.