How to Change Blogger Template in New Blogger Interface:

Some might use blogger old interface. But the old blogger interface will not be available in future. That means old interface retires.
So I write about ‘How to Change Blogger Template in New Blogger Interface’. Below are the step by step procedures to change the blogger template.
1. First download a new blogger template. Lots of templates are available in internet for free. Search for free blogger templates . Download a template which you want. The blogger template you downloaded will be an xml file or text file.
2. Login to blogger .You will get your list of blogs
3. Then go to ‘template’ section as given in below image.

4. Then click ‘Backup/restore’ button which will be at the right top corner.

5. A lightbox window will open with two options. First one ‘download full template’ is for making a backup of current template and second one ‘upload’ is for choosing a template from your computer and upload it to change the blogger theme.
If you want, you can take backup.
To change the template first click ‘choose’ and browse for the template you download and then click ‘upload’.

That’s all. Your template will be changed.
6. If you want to edit the template you uploaded click ‘edit html’ button.

A lightbox window will open and alert you. Click ‘proceed’ button.

7. After clicking ‘proceed’ button you can see the html code of your new blog template. Check the ‘expand widget templates’ option. 
8. Edit styles of widgets, body, text etc., And click ‘save template’ button.

Then click ‘close’ icon.
9. If you want to add gadgets, go to ‘layout’ option.

10. Click ‘add a gadget’ to add a gadget from a list of available gadgets. Arrange them by drag and drop. Don’t forget to save the changes by clicking ‘save arrangement’. 
That’s all. View your blog to see the changes.

One important thing to do:

One thing you must do is backup your blog html gadgets you added in old template and delete them before uploading your new template. After changing template restore them.

Why?

If you don’t delete them, those html codes may be hidden or vanished from your template ( I don’t know why. But sometimes it happens). But they may run. You can’t stop them working. I personally experienced it. I had a blog. Also I had added a gadget having a code for pop-up advertisements.
When I uploaded the template that html code gadget was vanished. I could not find it. But the advertisements had been showing on my blog. Later I realized pop-up adverts are irritating adverts. Also that advertising network suspended my account. But I could not remove their code from my blog since I could not find it. Adverts had been showing on my blog. So I deleted that blog and started this blog.
The problem with template Uploader may not come or template Uploader may not create the problem. But for safer side backup your gadgets codes, delete and restore after changing your template.