This article is an excellent introduction to home canning, and hits all the important basic steps.
For more detailed information (and: there really is much to know), allow me to encourage your readers to contact their local Extension Office. Every state has one, and nearly every county has an agent (or agents) who specialize in Food & Nutrition and are experts in home preservation. Populous counties may have several Master Preservers who can be counted on to answer questions, teach classes, and test pressure gauges. Also: an excellent on-line resource for any and all questions about home preservation is Georgia's Extension website: http://www.uga.edu/nchfp/

Sarah Colley Jones
County Extension Agent
Family & Consumer Sciences
Panola County, Texas