Each Wiki has a different shorthand for HTML unfortunately. "Splitbrain":http://wiki.splitbrain.org/wiki:markup_compare does a good job of comparing them and they aren't the same at all. Some relevant ones for Wikka Wiki are:

notextile..

//italic//
__underline__
##monospace##
++deleted++
~quoted text
%%source code%%
----- _Gives you a horizontal rule_
https://tongfamily.com should work as a URL automatically
[[https://www.tongfamily.com Tongfamily]]

Then they are very smart on lists, so wikka wiki knows that a tab or a ~ followed by an item is a list

1) item 1
2) item 2

Will generate a list while a tab and a dash (-) means unordered list

- item 1
- item 2

Tables are a little more complicated