[Help for a layman?]

I'm trying to make a custom image for my Steam account by combining two images.

I want to take the picture frame - style border from this image and combine it with the image of this image: (http://imgur.com/a/ROX9Z)

[How would I make a high quality custom flag image?]

Nevermind, it's done!

 

Thanks for the help!

[How would I make a high quality custom flag image?]

Thanks, both of you. I had no idea layers were this useful, I've spent the past hour or so trying to do it all pixel by pixel (I told you I was a noob.)

 

Iron67, what "grunge" effect did you use? I really like your example there. Also, how did you show that example below the text in your reply? I'd like to do that so I can ask for more help later or post on another thread. 

[How would I make a high quality custom flag image?]

Hi there! I'm a little new to the more advanced portion of editing software, but I've used Paint.net for random things for a few years and I know the most basic tools. I made this account specifically for this question.
 
To the point- I play a lot of online games, social media, stuff like that. I've always liked flags. When I was little I came up with a design similar to the UK's Union Flag (or the Union Jack), but instead of a blue field (background), white saltire (X), and red cross (+), mine had a dark red/crimson field, a gray saltire, and a black cross. 
 
I few years ago when I set up my steam profile, I found a cool HD square version of the Union Flag: (hopefully insert image here) ...and I want to make it with my colors. 

 

The issue is, the best two-years-younger me could do was a flat 64x64 pixel image with literally 3 colors. When I say 3 colors, I mean THREE COLORS. No shading, no variant within the color, nothing but solid red, gray, and black. 

 

My main questions are:

How can I edit the original Union Flag to have my colors, but still have the time-worn look and the used effect?

If I can't do that, how can I make up a new image with my colors, but not have it be 3 solid colors? PS- I would prefer not to do this pixel by pixel. I'm shooting for a 184x184 image, it would take a while to do it without shortcuts. 

 

PSS- How do I add images to the thread without putting it in the attachments? The original I mentioned is in the attachments by the way. I can't seem to find a way to make sure it's there, so my profile is the original Union Flag I mentioned. Sorry for noobiness, I made this account 40 minutes ago.