albo - 9:52 pm on Aug 13, 2012 (gmt 0)
I think you should read lucy24ís posts very carefully. She is wise. Also, you said: "I am using a template and it does have stylesheets, but I need some more knowledge about programming and CSS before going in them and working on the elements they have specified." Fine. But an essential part of CSS programming knowledge is the "C" - the Cascade - seeing how parents influence children, and seeing the priorities and strengths of selectors. For that, you could build your own style sheet and either link it *after* the template one or put it in the head section of your html.
As for font-sizes, give up on being pixel-perfect. Aim for legibility across browsers. I'm typing this comment now on an iPad in a surprisingly small font-size: partially my fault, because I've not clicked to zoom. But the rest of this page appears in a very decent and legible font size. In many circles it's argued that a fair method is to go with initial font-size 100%, then go with either ems or percentages thereafter (remembering *also* to do the math to adjust margins and padding accordingly). One *brief* (thank goodness) book that goes into all this is Ethan Marcotte's Responsive Web Design. Of course, for the depths, plunge into master Eric Meyer's stuff.