Choose the program in which you'll create your digital art. You have many program options available. Whichever program you use, familiarize yourself with the program so that you have a thorough understanding of the tools available.
Select the paper type on which you'll print. Unless you create a poster, you may want to go with a card stock or a thick art paper. This gives the piece added stability. Also, depending upon your goals for the project, the paper itself can become a part of the design element if you choose a paper with a design on it.
Set the document resolution parameters in your graphics program. Usually you find this under "File" menu. Printing a document requires a higher resolution than what you would need to post it on a website---72 dots per inch (dpi) for web verses at least 300 dpi for print. Since you're making pin up art, you want to choose at least 300 dpi. Depending upon the project and your plans for the art, you may want to opt for an even higher resolution, perhaps 600 dpi, to give you the ability to enlarge the document without distortion.
Select the right color scheme for your document and set your document parameters to it. You want to choose the CMYK option. (The other option, RGB, is primarily used for digital pieces that people view on the web only.)
Create your digital art piece. Make sure that when you set the dimensions of the piece---let's say you're making a piece of artwork that measure 18 inches by 24 inches---you leave a little "bleed" room, an inch or more around all the edges. This allows you to frame the piece without covering the artwork.
Save the piece as a PDF (portable document format). To do this, go to your "File" menu and choose "Print". Under your printer options, select the PDF option. If you do not have a printer or if you do not see the option to create a PDF in your printer options, you can download a PDF maker from the Internet.
Burn the PDF onto a CD to take to your local printing shop (unless you yourself have the tools you need to print out your digital art in the size you want.)