There are many basic walkthroughs on the internet on how to use markdown. I will simply relay some basics here for those interested.

Tutorial Links:

Markdown Tutorial
Markdown Cheatsheet
Ultimate Guide

Here are some quick tips:

Headers

Using the pound sign "#" up to 5 times in a row "#####" will give you Heading sized text decreasing from largest to smallest with the number of "#" used.
# example
## example

italics

Simply surround a word or phrase with a single asterisk "*" on each side or surround with an underscore "_"
*example*
_example_

Bold

Simply surround a word of phrase with a double asterisk "**"
**example**

Links

Use the format [TEXTgoesHere inside brackets]( httpLinkGoesHere inside parentheses)
[exampleTEXT](httpLink. com)

Pictures

Use the same format for a link above and place an exclamation "!" in front. The TEXT inside the brakets is "Alt" text used to assist the blind. You can leave it blank if you wish. The link to the picture is placed inside parentheses like above.

New line without new paragraph

In order
to do this
you need
to place
at least 2 spaces
at the end of each line.

That should be enough to get you started. Refer to the links above to learn more and in greater detail.