The text beneath the image says you have found a key that does not fit the lock of this particular door. Here you should remember the locked mill in riddle III. Go back there and you will now be able to click that door, leading you to a modified version of the diary entry from that riddle. You will also find a “Piece of Paper” which is needed to solve a future riddle.

In this version of the diary entry, there are black bars covering the ten plagues. Use some image editing tool to cut these bars out and overlay them in the main image of riddle VII. Put the bars with their left end at the vertical line, by the icon corresponding with the plauge the bar covered.

The icons from top to bottom are:

tears turning red
reptiles
biting
insects
farm animals
symptoms
pouring (a bit stretched I guess, but a lightning probably means a storm)
swarming
shadow
eldest son (the skull represents the death of them)

Be very exact when you are cutting out the bars from the diary entry image. You must get the bar, the whole bar, and nothing but the bar. Also it is important that you place the beginning of the bar EXACTLY at the vertical line. When you’ve done this, use the first visible letter at the end of each bar. Read them in the order the plagues appear in the diary entry.