Hi Yusniar welcome to #steemit. Probably you have a lot of questions about Steemit and the easiest way to get proper answer is from reading the Official website FAQ:
(https://steemit.com/faq.html).

Your images got a html error code problem. Do not panic, just click on edit and removed the error code. After that, re-upload your images and post again.

Have fun exploring and posting your experiences in Steemit. Cheers!