Hi,
browsers already have print function so this is usually an overkill, but you can add a button with href set to javascript:window.print()
Print output in broser depends on css so if your print style does not work ok as it is, you can add new css file include in your template, which will be used just for printing and import it to Seblod like this (take care that you will need to specify the right path), you can use Code pack CSS plugin
http://www.seblod.com/products/1854
or put this in seblod configuration, site tab, but then it will be included on all pages so it is better to use code pack
@import url("fineprint.css") print;