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.