Illustration Tutorials and Advice Superthread

How do you replace pre-existing flags in historical photos with your own flags in GIMP? For example, how do I remove the US flag from the Iwo Jima photo and replace it with a flag from my Chinese TL?
create a layer above the picture and look at the shadows in the flag. Use a paintbrush to trace them (use medium grey). You don't have to be too precise since you're going to then gausian blur them. in another layer, Trace the highlights the same way in white.

since this is the chinese flag, trace the flag's contours on another layer using the same grey as the red stripes on the US flag in that picture to make the field. You would then fiddle around with the noise filter to so that it doesn't look too flat.

Simply take the stars from the chinese flag (you can find a picture of it on wikipedia) and put them on a layer above the play field one. Use the canton to align the stars and erase anything that wouldn't show due to a fold

now you should have five layers, from bottom to top: original picture, chinese flag field, stars, highlights & shadows. Change the highlights layer property to "lighten" and the shadow layer to "darken". change the opacity value of each until they look about right.
I've been getting a handle on alternate wikiboxes but a few things continue to be a bit of a puzzle.

I was trying to create an alternate wikibox for a president. I went into the Sanbox and use infobox officeholder as the template and then looked at President Garfield's as how to do one very similar to his. But it kept coming out wonky. I wanted my fake president to have been president-senate-state house but it kept coming out as state house-president-senate. A list that I wanted from higher to lower office was getting all jumbled.

How can I fix that?

I'm editing visually. My skills are... developing, lol.