Pics or it didn't happen!

I really, really wanted to put pictures up on the front-page parts of Somewhere Else Entirely, but I have failed because I don't know where to get suitable pictures from.

I can figure out how to upload the things and I've seen a guide on how to insert them into the HTML page in a suitable place, but my problem is that I don't know where to find suitable public domain images I can freely use. I wanted to use real images. I don't think I can use the drawing programs that some authors have used to make pictures because (i) my drawing sucks, I'm strictly a text-kinda girl, and (ii) most of them are for Windows which I don't speak.

I didn't really want to get into paying for the things or involving complex copyright issues. So, anyone tell me places to go for freely (in all senses) available images?

For example:

ch. 1 - A range of mountains in the distance.
ch. 2 - A hippopotamus.
ch. 3 - A wagon or wagons - not, probably the American-style covered wagon though.
ch. 4 - A large half-timbered building that might be a palace.

etc. etc.

all suggestions gratefully received.

Penny