This is how a post will look like when just placing an Image without text
basic posting. best is if you are a Dragon on the site that enables you to use
Html tags to use on the upper right of the box the " Visual Editor "
Dont6 forget to save so that your changes go into the Box.

just an image:

<img src="http://i.imgur.com/ZqYYgVl.jpg" alt="">

in the visual editor you can just mark " Click the Image " to add aditional features
if you Center the Image it will look like this:

<div style="text-align: center;"><img src="http://i.imgur.com/ZqYYgVl.jpg" alt=""></div>

Now the next stepp if you want to Hyperlink and resize your image
Edit in the Visual editor your Image , In the box were you Placed the Image you see the 
Option " Width: " there you can add the sizing example 850Px.
by doing this your Text will look like this but still not clickable.

<div style="text-align: center;"><img src="http://i.imgur.com/ZqYYgVl.jpg" alt="" width="850px"></div> 

To make it clickable mark the Image again in the Visual editor and right next to the option were you
add your Image you will see the Option Hyperlink just add in that box the same Link you used for your Image.
your text will look like this adding the feature to open the Image on clicking in the same window.

<div style="text-align: center;"><a href="http://i.imgur.com/ZqYYgVl.jpg"><img src="http://i.imgur.com/ZqYYgVl.jpg" alt="" width="850px"></a></div> 

Now f you wish to have the Image open'd in a new window you will need to add the text manually into the Box.
you will add this line 

target="_blank"

the changes that you now do manually are always in the first line of the Image text. were you have <a href= !!
to make it clickable in a new window after adding target="_blank" your text will look like this.
target="_blank" is added just after the first Image link.

<div style="text-align: center;"><a href="http://i.imgur.com/ZqYYgVl.jpg"target="_blank"><img src="http://i.imgur.com/ZqYYgVl.jpg" alt="" width="850px"></a></div> 

To have the Post more advanced adding a Lightbox Option , means that the image will open over the same Page you can use
a line that you place just after the <a in front of your first image link. doing this you actually dont need to have 
the target="_blank" line as a Lightbox option will replace that feature.
the line you add looks like this

class="ulightbox ph-link"

and after ading it to the line your Html text will change to this

<div style="text-align: center;"><a class="ulightbox ph-link" href="http://i.imgur.com/ZqYYgVl.jpg"><img src="http://i.imgur.com/ZqYYgVl.jpg" alt="" width="850px"></a></div>

For a Lightbox effect it is Important that the Image is Sized with the Line width="850px" that you see at the end of the Image post 
right after the alt="" 
actually also an option after some experience that you can add manually.


Shortcut:
you can also try using this text line just by Copy Paste into the Posting box. naturally you will have to put your Image Link
replacing this 2 Lines
REPLACE THIS WITH YOUR LINK
not disgarding the Quotes.
Just try it out if it goes wrong you have the Option to Delete or edit your Post.


<div style="text-align: center;"><a class="ulightbox ph-link" href="REPLACE THIS WITH YOUR LINK"><img src="REPLACE THIS WITH YOUR LINK" alt="" width="850px"></a></div>