See http://answers.yahoo.com/search/search_result;_ylt=AnX6gvAjq_INpcAVx07xKepIzKIX?p=how+do+I+make+a+photo+with+only+one+color for well over 2,000 times that this question has been asked before. Each time it will have 5 answers or more, so you will have 10,000 answers to choose from. One of them will work with your software.
Or, come back and tell us exactly what image editting program you are using and maybe there is someone here who knows about that program who cangive you a meaningful answer.
Or, since you want to buy a program consider Photoshop Elements 5.0.
Start with a color photo. If you want to add color to a black and white photo, you will have to be very careful, patient and skillful with the paintbrush tool.
This is one way that you can do it in Photoshop Elements. Maybe this is helpful for other image editors as well. It would be helpful to print this out and follow along. It's easy to do, but you must do the steps in order. Perhaps your own image editor has similar commands. If not, you might want to add details or post a new question to tell us what software you will be using.
1. Open the image you wish to alter.
2. Save the image using a different name than the original name so that you don't lose your original.
3. Use any selection tool you wish to outline the object whose color you wish to preserve. The Magnetic Lasso Tool is pretty quick, but the regular Lasso Tool might be more precise.
3-A. Use the erase tool to erase any color that you do NOT wish to preserve.
4. Hit [CTRL]+[C] to copy the selection.
5. Hit [SHIFT]+[CTRL]+[N] to make a new blank layer.
(Name it if you want, but you can accept "Layer 1.")
6. Hit [CTRL]+[V] to place the selection in the blank layer.
7. Move back to the background layer by clicking on that layer in the layers palette. (on the right of your screen)
8. Hit [CTRL]+[SHIFT]+[U] to remove all color.
8-A. ALTERNATE APPROACH No. 1: Hit [CTRL]+[U] and use sliders to desaturate, leaving a hint of color present.
8-B. ALTERNATE APPROACH No. 2: Use a "Convert to Black and White" utility, if your software offers this. In Photoshop Elements, the command is [ALT]+[CTRL]+[B].
9. Hit [CTRL]+[SHIFT]+[E] to merge the layers.
10. Save your work.