newbie html forms primer help

I need some help with html forms. I primer on html forms and variables is much needed. Anybody have some code snipets to share? I'm getting acquainted with $HTTP_POST_VARS but need some help in accomplishing a couple of things. I'd like to collect all "checkbox" input variables and stick them together in a comma delimited string. I'd also like to display the names and values of the all posted variables. In another language I'm familiar with, this looks like: [formvariables name=thevarname][name]=[value]<BR>[/formvariables] For passed checkbox input var doh, where values were blah and bleck, the above code would display: doh=blah doh=bleck How do I do this with php?