Quick question about gimp, possibly photoshop too

I created a banner in gimp. It is purple. I inserted a few pics, but the background on the pics is white. So, I have the pics w/white backgrounds on purple backgrounds. How do I get the white color on the pic backgrounds to purple? For instance, I have a pic of a toy train. When I insert the pic, the white background the train is on sticks out. I want it to look like the train is part of the banner, not just a square image sitting on the banner.

This is my first attempt at using these type of programs.

 

Well in Photoshop we usually do that by 2 main options.

Either erase the BG with Magic Eraser, BG Eraser.

Or

Use the dropper tool to collect the purple and then use the bucket tool to insert that colour, not sure about GIMP, been ages since I used it.

 

Can't say I know anything about gimp, but if you have access to photoshop try this:
Select->color range (pick white with the colour picker) then adjust 'fuzziness' so only the white is selected.
Click OK, then (possibly feather the selection by 1 pixel) delete the selection so the purple background will show through.

 

It's gonna have to be ginp specific I guess. I only have GIMP, not photoshop. I tryed painting the white, but I cant get in between parts of the train to get the white out without painting over the train.

I am having real problems, but I dont know what to search for in google to find a tutorial.

 

Have a look here for gimp specific techniques, Gimp has similar facilities:

http://en.wikibooks.org/wiki/The_GIMP/Selection_Techniques

 

you can use the freehand tool to cut the white pieces out of your image or you can just search for a render of a train pic.you can try planet render

 

Still bored? PM me with your msn/skype id, I'll give you a quick demonstration if you want.

 

You can find some good tutorials for GIMP at:
http://www.gimp.org/tutorials/
http://gimp-tutorials.net/