Font size

the sub forum for general help would be http://ww.wp.xz.cn/support/forum/how-to-and-troubleshooting#postform

if it is about themes or templates, http://ww.wp.xz.cn/support/forum/themes-and-templates#postform

if it is for a specific theme, start a topic in the theme’s support section, for example if the theme is Twenty Twelve http://ww.wp.xz.cn/support/theme/twentytwelve (scrol down to the form)

if your theme is commercial or not from http://ww.wp.xz.cn/themes/, plesse contact the theme’s developer directly; http://codex.ww.wp.xz.cn/Forum_Welcome#Commercial_Products

font-size CSS:
http://www.w3schools.com/cssref/pr_font_font-size.asp

please review the ‘forum guidelines’ http://codex.ww.wp.xz.cn/Forum_Welcome

http://codex.ww.wp.xz.cn/Forum_Welcome#Include_as_much_information_as_possible

is there anywhere I can copy and paste the code from my website for someone to assist?

generally, for formatting questions, a link to your site would be required.

for questions regarding your theme, possibly start a new topic under

http://ww.wp.xz.cn/support/theme/modularity-lite

(the input form is at the bottom of that page)

alternatively, it is really only about formatting, try asking at a CSS forum like http://csscreator.com/forum