Editing pics?

[Candy Custard]

Oooh help me please some nice kind person.

Sorry if this appears to be off topic, but I will post the resulting messy pics if I can get this sorted.

I recently did a set of sploshy pictures, but they all need rotating, and when I do rotate them it turns from a rectangle to a square, gets distorted and makes me look far wider than I am.

I've tried a few things (paint, irfanview, finepix software) but nothing seems to be working. Any ideas?

I need to know what I can do as have more pics to do for a rather epic session I'm planning this Tuesday and will be doing pics then too with the same camera.

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