Here's a tip for you: use stick figures. I'm terrible with anatomy myself, but I discovered that I could improve the quality of my human drawings drastically if I sketched a stick figure of the person I'm drawing, then draw them over it. The important thing in this case is to give the stick figure shoulders. Here's an example:
It's far from perfect, but at least believably in proportion. Notice how the area between the head and shoulders becomes the neck, and the hands and feet are part of the lines for arms and legs, not added to the ends of them. Also, the waist is above the point where the legs split off. The arms should probably be thinner than what I've drawn and the head should be a little bigger (the hair should be built around the head circle, but I erased a few times and ended up cutting a bit off), but anyway I just sketched this out in about thirty seconds so I could show you. If you can draw a reasonably-proportioned stick figure, you can draw figures a bit better than if you just try to go at it without any frame. It's like giving them a little skeleton.
I got better at drawing stick figures (that's right, there are different levels of stick-figure-drawing skill) by copying stuff from
XKCD. I'm thinking of writing a how-to-draw book about drawing based on stick figures.
But I should probably get better at drawing myself first... (You can see examples of my skill level by going to the "Daily Underground" link in my signature. I add a new strip every weekday and occasionally a bonus one or two on the weekends.)
As for resizing images and changing formats, the best program I know of is
IrfanView. Very easy to resize, crop, and convert the format of the image.