how to make my blog private?

See if this plugin will work for you:
https://blog.taragana.com/index.php/archive/angsumans-authenticated-wordpress-plugin-password-protection-for-your-wordpress-blog/

i tried that, but it makes guest to register and they can’t view my blog design. What i look for is “you can view but you can’t read the content” please help me

If I can view something I can read it. Not sure what you are saying.

Check out Plugins/Restriction.

something like you go to my blog
https://babienhu.com/blog
you can view the design and everything except my blog entries. except if you sign up, then you can read my entries

just a suggestion, but why dont you show a few sample posts, and then password protect the others, otherwise, why will people sign up if they dont know if your posts are good or not.

once people sign up, you could tell them the password to your posts

oh, this blog is for friends, and yes they can read after they registered. I just don’t like guest read it.