I had cerate the file and used them to create the blog post and website. And now I wanted to rearrange the file in the design manager so it is more clear and easy to find the specific file. If I rearrange it, will it affect my blog post that already created? And how to check whether that file is being used in the current web/post so that I can delete the unwanted template.
Not sure what exactly you are rearranging. Are you rearranging modules within the blog post page? Are you moving the post template to a new directory?
For the second question:
In the Design Manager, while you have the module or template selected, you should see in the left sidebar an actions dropdown. Click on it and you should then see Show Dependents. This will list all pages that are dependent on this item.
Gotchya! So the answer depends a lot on how you initially built the your template. If you built it locally, then you might have some issues with incorrect paths, but if you built it completely in the design manager, you should be fine.
I would suggest performing a test.
Clone a template
Create a new css file that does something obvious on the page like *{ border: 1px solid red}
Add the new css file to the cloned template.
Create a page from the new template and confirm that the there is a border around everything
Now move the css file.
Open the page in an incognito window and confirm your results
Not sure what exactly you are rearranging. Are you rearranging modules within the blog post page? Are you moving the post template to a new directory?
For the second question:
In the Design Manager, while you have the module or template selected, you should see in the left sidebar an actions dropdown. Click on it and you should then see Show Dependents. This will list all pages that are dependent on this item.
For the first question, I want to arrange the file in the design manager into new directory so that I can put all the CSS in one file and module in one file and ... But then I scare that if I move it to a new directory, it will affect the existing blog/page that uses that file.
Gotchya! So the answer depends a lot on how you initially built the your template. If you built it locally, then you might have some issues with incorrect paths, but if you built it completely in the design manager, you should be fine.
I would suggest performing a test.
Clone a template
Create a new css file that does something obvious on the page like *{ border: 1px solid red}
Add the new css file to the cloned template.
Create a page from the new template and confirm that the there is a border around everything
Now move the css file.
Open the page in an incognito window and confirm your results