Hi there Nishad appreciate that you take the time to write for us beginners :)

Here are also some useful contents:

• https://steemit.com/steemit/@pkattera/the-perfect-dimensions-for-the-main-image-in-your-steemit-com-post-are
• https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet
• https://steemit.com/steemit/@bkkshadow/steemit-how-to-less-than-center-greater-than-your-pictures

Have a nice day!