How to upload .psd template to a website?

Well, if you are wanting other people to be able to change the template as well, then you will need to leave it as a .psd, upload it to a website like savefile.com, and post the link to the file in the website. Basically you will just need to find a web-based file-hosting service that suits your needs and then link the download page for people to grab the template from.