I'm using a creaky old version of Internet Explorer, so I'm limited as to what I can post - or see....
There's an icon in the second row of buttons above the "post" box.
It is a tiny icon of a green tree in a photo frame. That's the "Insert/Edit Image" function.
Click on that,
insert your "link" into the "Image URL" line on the "General" tab,
type in some sort of 'description' below,
check the SIZE of the photo on the "Appearance" tab - must be below 775 px in either direction or one gets those nasty "scroll" bars around your pix - and you can insert the "775" px size in EITHER box, then hit "TAB" on your KEYBOARD and the other number value will be automatically adjusted - or press "shift" while hitting "TAB" if you adjust the SECOND px number and want the 1st px number to automatically adjust....
Then hit the "INSERT" button at the bottom left of the "insert/edit image" screen....
And that should do it...
That's about what Baba Yaga's post had to say, if I remember correctly...
Best results...