How to change the template of the existing blogspot template and i dont want to loss my posts? and where can i get free template and how to upload it?
you can just login to your blogger account and there should be an option for "templates" which you select. there are lot of stock templates you can use. just select a template you like and set as your default template. your posts are stored in a database and changing the template will not make you loose any posts. people change templates all the time