Open a new image in Adobe Photoshop by going to "File" and "New." Set the measurements to 600-pixel width and 800-pixel height. Make sure you set the image background to transparent.
Search for wood and brown paper bag-like textures on graphics websites and save them to your computer. You can do an online search, or, if you already know of a site that offers textures, go there. Once you have saved them, open the wood graphic in Photoshop, go to "Select" and "Select All," then go to "Edit" to copy it, and then paste it onto your new, blank image.
Use the "Rectangle" tool in the panel to the left to create a new selection on your image with the wood texture, leaving a few pixels of your last layer visible so that you get a frame. Open the paper-like texture, select it, copy and then paste it into the new selection.
Select the "Polygonal Lasso" tool in the tools panel to the left by pressing and holding the "Lasso" tool icon (the polygonal lasso tool is the second option when you press the icon). Click an irregular selection around the paper texture you just pasted to make it look like torn paper. Do little bits at a time, clicking to your starting point on the outside frame, and hit your delete key to clear.
Click and hold on the "Dodge Tool" in the panel on the left to bring up all the options under the icon. Select the "Burn Tool" (second option) and run your cursor over the edges you just created on the paper texture selection.
Using the "Type Tool," select a Western-style font and type "Wanted" at the top of your page, not in the frame but in the torn paper area. At the bottom of the page, type a message about a monetary reward, or someone's name (the name of whoever your "wanted" subject is going to be).
Open an image of yourself or another person you would like to be the focus of the poster. A high resolution photo may be preferable because you can resize it to suit your needs. Select the "Lasso" tool, making sure the pixel amount in the "Feather" box at the left top of your program is set to a number higher than 0. Cut around the individual's photo until you have it completely selected.
Paste the person's photo you just cut out into the middle of the poster, and you're done.