You can upload your pics to photobucket.com if you`d like. That`s what I use, and I`m sure a bunch of others here use it too. It`s free, and there`s tons of options including editing, cropping and resizing.
If you use it, once you`ve uploaded them, under the photo you`d like to post there will be a few different scripts.. like e-mail, direct link, etc. The last one says IMG code, and if you highlight that and copy it, all you have to do is paste it onto PT and voila! Sigs work the same way.

Here`s a picture if it helps: