Logging in
On your own site, you will need to first connect to jetpack which will link your personal site login to the WordPress platform. From now on, you will be directed to login in via the WordPress platform. This will be a lot less confusing if you just use the same username and password! Sometimes you may get a random error, I think it is jetpack error 10520. This is easily worked around by clearing your cache. (Chrome > Clear Browsing Data. Usually just checking the top four items and clearing for the past week works fine)
Your Profile
You will most likely only need to edit your profile once. You can navigate to your profile once you have logged in by clicking on your name in the upper right hand corner. Edit your display name and bio. Your avatar is linked from the WordPress Platform, so you will have to change that on your WordPress profile. Once you change the avatar there, it will show up on your site, although you may need to clear your cache again at this point. (Note: your browser is smart and remembers what certain content looks like on your site so your old avatar may be cached!)
Posts
Images
Simply click Add Media! or if you want an image as a banner, set a featured image. Remember that the pictures you use must be labeled for reuse! You are not exempt as a student from copyright infringement!
Embeds
Basically you can embed all sort of content in your posts, not just pictures. This is primarily done via shortcodes which are very well documented here. First, you need to activate the iframe plugin on your site though. It is also a good idea to enter the shortcode in the text editor instead of the visual editor.
Mobile (?)
This is a great idea for blogging on the go. Make sure to turn geotagging on so you can later find your exact location at the time of the post. It is also need to immediately upload an image with that site specific post!